Niners rookie wide receiver Ronald Johnson with his best buddy at the NFL Combine.

If sixth-round pick Ronald Johnson doesn’t make it in the NFL, one thing seems absolutely certain: It won’t be for lack of effort.

The Niners have raved about Johnson’s passion since they drafted the USC wide receiver, but they might have undersold his love for the game.

Johnson does more than eat, sleep and breathe football. He actually sleeps with his football.

In fact, Johnson said he takes his football everywhere. As I spoke with him today after the third day of the 49ers four-day minicamp, Johnson said his football, which he packed for his trip from Muskegon, Mich., was in his car.

He used to sleep with an NCAA football at USC, but he’s since switched to an official NFL ball. They’re the same size, but Johnson says they have a different feel.

Oh, another thing – he’s written something on his ball: Son.

“It sounds strange, but I have a relationship with the football,” Johnson said. “… I actually sleep with it. It sounds weird, but I do it. Just to get that extra edge everyone else doesn’t have.”

Johnson is all about finding an edge. Ever heard of athletes doing workouts to strengthen their … hip flexors? Johnson said he does those to increase his flexibility so he can “make the great catches” and, of course, “get the extra edge.”

Johnson said he’s routinely been up until 2 a.m. recently cranking out his daily regimen of 300 sit-ups and 300 push-ups (fingertip push-ups to strengthen his hands), studying his playbook (he said he’s written so many notes in it he can barely make out the plays) and playing with his football.

“I like to see how long I can play with it and not let it hit the ground,” he said.

Johnson will throw his football behind his back. He’ll toss it up, let it fall below his waist and practice snatching it by the nose with one hand – anything to make catching it become “second nature.”

He said he’s been constantly throwing a football to himself during practices this week. His teammates have noticed and today, he said, they threw five footballs at him, firing one after another. He caught them all, he said, smiling.

Johnson (5-10, 185), who was projected as a mid-round draft pick, instead fell to the middle of the sixth round, the 24th wide receiver off the board.

He said his disappointing draft experience has only increased his drive.

“It gives me a lot of fuel because I do things right,” he said. “I do what I have to do to be considered the best and I’m not considered up there right now. So I’ll keep doing what I have to do so I can be the best.”

• Johnson, who had a 10-day stay in the Bay Area earlier in the offseason, said he’s unsure if he’ll be staying after the minicamp to continue throwing sessions with quarterback Alex Smith and other wide receivers. He said Smith has paid for his plane tickets to the Bay Area.

Aldon Smith? He’s “just scratching the surface of his potential.”

Colin Kaepernick? An excellent second-round value who needs polishing.

Chris Culliver? A raw cornerback with spectacular athletic ability.

CBS Sports draft analyst Rob Rang views each of the Niners’ top three draft picks as “ascending talents” who have an asterisk attached: They will need some intense tutoring to get NFL ready. (Unfortunately for the 49ers, it appears school won’t be in session soon.)

“Obviously with (Jim) Harbaugh’s staff, they are confident in their abilities,” Rang said. “And they are a group of players, these initial three, who do need coaching up. So it’s like the 49ers scouts are now putting it on the shoulders of the coaching staff and saying ‘OK, you’re going to have coach these guys up and you’re going to have to earn your money.’ They got three legitimately talented players at three obvious areas of concern.”

Here are Rang’s thoughts on Smith, Kaepernick and Culliver. (Since this got a bit lengthy, I’ll follow up with a blog on Rang talking Kendall Hunter and Ronald Johnson):

ALDON SMITH, DE/LB, MISSOURI

Rang would have liked this pick better if Smith weighed about 10 fewer pounds.

Smith, who checks in at 6-foot-4 and 265 pounds at 21 years old, figures to get bigger. And just how big can he get and still be an effective 3-4 outside linebacker? He’s already in the same weight class of some of his heavier peers in New England’s Adalius Thomas (6-2, 270), Pittsburgh’s LaMarr Woodley (6-2, 265) and Dallas’ DeMarcus Ware (6-4, 262).

“I love the physical potential of him, but in my conversations with people around the league, and they certainly echo my belief, is that he was a better fit as a 4-3 defensive end,” Rang said. “Whatever he is — 267 pounds? — he is just naturally going to grow into a bigger player considering his very young age and the rangy build he has. He is just going to continue to grow and there are just not a lot of successful 280-pound outside linebackers.”

• Rang noted Smith’s stiffness — a quality general manger Trent Baalke acknowledged during his film-session review of the draftees with the media (Baalke said such stiffness was not uncommon).

“He’s not as fluid as I would like as far as an outside linebacker,” Rang said. “He’s an explosive player that has good burst upfield. And when he sees the quarterback or a ball carrier he does have a great burst to close, which is absolutely critical for being a successful pass rusher. So I like that.

“I don’t know that he has a lot of bend to him. So when he’s trying to go around an offensive tackle, for example, and he’s got to turn his body to go around the edge, he doesn’t have that great flexibility — what we call ‘dip and rip’ past the offensive tackle.”

I thought the dip-and-rip comment was interesting. Baalke believes Smith’s stiffness will really only show up when he drops into coverage – a duty he’s expected to perform sparingly in the NFL.

Rang did say Smith could compensate for some of his lack of fluidity with his remarkably long arms – he possesses an 83 7/8-inch wing span.

• Parting thoughts: “Physically, he’s a pretty extraordinary athlete and he showed the ability to be productive immediately in college,” Rang said. “I do think he’s an ascending player who is just scratching the surface of his potential, but, again, I really thought his best bet was as a 4-3 defensive end.”

COLIN KAEPERNICK, QB, NEVADA

Rang believes Christian Ponder, selected by Minnesota with the No. 12 overall pick, is the most NFL-ready quarterback in the draft. But he says Ponder has limited upside – “he kind of is who he is.”

Kapernick, then, appears to be the anti-Ponder: A not-ready-for-prime-time project with plenty of room for growth.

“I do like the value 49ers got there,” Rang said. “I do think Kaepernick is a very nice fit for them in terms of he is a player they’ll need to polish just because of the throwing motion and he’s making that transition from the Pistol offense. But I think that’s something the 49ers can afford to do, especially with Jim Harbaugh there.”

• The only quarterback in NCAA history to pass for 10,000 yards and rush for 4,000. The only quarterback in NCAA history to rush for over 1,000 yards in three consecutive seasons. The only quarterback to blah, blah, blah …

Rang says Kaepernick’s stats are impressive. And somewhat irrelevant given the system he played in and the competition he faced.

“You’ve got to throw (the stats) out the window,” Rang said. “I assure you that whoever the quarterback is at Nevada next year, his numbers won’t be as good certainly, but he’s going to put up impressive numbers as well. It’s just that (Nevada coach) Chris Ault is a marvel.”

CHRIS CULLIVER, CB, SOUTH CAROLINA

Is he a cornerback? Is he a safety? Rang, a big fan of this pick, believes Culliver could be talented enough to perform either duty at the NFL level.

Culliver started two seasons at safety in college before making seven starts at cornerback in an injury shortened senior season. He earned second-team all-SEC honors as a junior and was a preseason All-American entering his final season. His 4.4-second 40-yard dash at the NFL Combine was tied for the third-fastest among cornerbacks and his vertical jump (38 5/8 inches) was tied for the second-best mark.

“He’s a player that I think can play corner and he can play safety and I’m not sure where he’s going to play best at. But he showed the skill set to be a quality player at either position,” Rang said. “… He’s a spectacular athlete and he did it against elite competition. If you want to play him as a press corner then he’s a little raw, certainly, but he has the traits you’re looking for. And as a safety he has those traits as well. The proof is in the pudding with him — he’s already done it at a high level as a free safety.”

• ESPN’s Mel Kiper said he graded Culliver as a sixth-round pick moments after he was selected, but Rang says other teams were waiting to grab Culliver if the Niners had passed with the 80th overall pick.

“I can tell you from talking to some other clubs that in the next, say 10 picks or so, he was very much on the radar,” Rang said. “That was about where he was going to go.”

David Carr had a career-high 83.5 passer rating with Greg Roman as his quarterbacks coach in 2004. -- AP

As a general rule, NFL head coaches don’t enlist former Division III defensive linemen to help educate their $60 million quarterbacks.

But Packers defensive coordinator Dom Capers says Greg Roman isn’t a typical coach.

In 2004, Capers, then the Texans head coach, examined his staff and decided the 49ers offensive coordinator would help mentor struggling quarterback David Carr, the No. 1 overall pick in the 2002 draft. Capers moved Roman from tight ends coach to quarterbacks coach – an unlikely title for a former defensive lineman at John Carroll University with scant hands-on experience with quarterbacks.

“He understood the total concept so well that I ended up making him the quarterbacks coach,” Capers said in a phone interview this week. “That was just because I felt he was the best guy for the job and he understood defense. He understood how to attack things. He not only knew the protections in the pass game, but he knew the route concepts.”

By 2004, Roman was in his seventh season working for Capers – the first four in Carolina – and had been given countless titles: defensive quality control coach, offensive quality control coach, offensive assistant, assistant offensive line coach and tight ends coach.

Capers felt Roman, then 31, had received a comprehensive education. So although Roman had never worked with quarterbacks, his mastery of other offensive positions and ability to recognize a defense’s weakness had him tutoring Carr.

In two seasons with Roman as his quarterbacks coach, Carr had 30 touchdowns, 25 interceptions and an 80.5 passer rating. In his three other seasons as Houston’s starter, Carr had 29 touchdowns, 40 interceptions and a 71.7 rating.

“I think some people might see it as being an unusual move,” Capers said. “But when you sit in the meeting room and you know that you’ve got a guy in there that understands not only the run game, but the protections and has also been involved in the pass game because he’s coached the tight ends … I just felt at the time that Greg was the most qualified guy to move to the quarterback position.”

Seven years later, it appears Roman will be working with another former No. 1 overall pick in Alex Smith, who will count Roman as his seventh offensive coordinator.

“I think what Greg has that will enable him be an outstanding coordinator is that he’s worked in all those different areas,” Capers said. “And he’s got a real good understanding of all facets of the game.”

• Carr, 31, hasn’t started a game since 2007 and has thrown just 58 passes the past three seasons.

While Jim Harbaugh has publicly wooed Smith this offseason, he’s been tight-lipped regarding Carr, his only quarterback under contract for 2011.

Roman, who was in Houston for Carr’s first four seasons, says the former No. 1 overall pick might have had a different career if it had started differently. As a rookie, Carr started all 16 games for an expansion team and was sacked 76 times, an NFL record.

“No one will ever know,” Roman said. “But I do think it was definitely a factor. It certainly didn’t help his maturation.”

There were plenty of good questions, some of which had me racking my brain (and pestering colleagues) for answers. Here’s the first batch:

Q: Do you see Colin Kaepernick playing on situational basis, like 3rd & Short or Goal-line behind Smith ala Tebow in Denver? @DannyOnAir

A: Yes. Jim Harbaugh has a reputation for utilizing whatever talent he has available — my sense is that if Joe Nedney had a masterful hard count, Harbaugh would line him up behind center on fourth-and-one to hut, HUT!! the defense offside.

With that in mind, if Kaepernick isn’t starting, I’d expect to see Harbaugh and Greg Roman take advantage of his running ability. When asked about possibly trotting out the Wildcat for Kaepernick, Harbaugh said his rookie quarterback had the athletic ability to execute all the “quarterback-driven runs” and rollouts in the playbook.

Harbaugh made full use of Josh Johnson’s wheels at the University of San Diego. In two seasons as the starter under Harbaugh, Johnson rushed for 1,065 yards on 188 carries and scored 15 touchdowns.

Q: How do you see the 49ers using Kendall Hunter? @JayManDefenseLaw

A: I think Hunter will have a chance to be Frank Gore’s primary backup and could also be in the mix to return kickoffs (he returned eight kickoffs at Oklahoma State). Trent Baalke said he doesn’t view Hunter as strictly a situational, change-of-pace back, which means Anthony Dixon will have competition for carries.

Dixon showed nimble feet as a rookie, but the Niners would prefer him to be more battering ram than Baryshnikov: He’s a 233-pound power back and didn’t consistently run like one. Dixon averaged 3.4 yards per carry and didn’t finish with a flourish, collecting 39 yards on 17 carries in the final two games.

Q: Have there been any successful S to CB conversions in the past? @hiRicken

A: A stumper. In the interest of full disclosure, it required a consultation with fellow NFL sicko and colleague Phil Barber to come up with the name of … Carnell Lake.

The Steelers’ All-Pro safety voluntarily (and successfully) moved to cornerback when Rod Woodson, a future safety, missed most of the 1995 season with a torn ACL. Lake made the Pro Bowl as a cornerback in 1995. The 6-foot-1, 210-pound Lake also saw time at cornerback in two other seasons during his 12-year career.

I’m guessing the question is inspired by rookie cornerback Chris Culliver? The 49ers’ third-round pick spent two years at safety at South Carolina before transitioning to cornerback for his injury shortened senior season. The difference between Culliver and Lake, of course, is that Culliver is beginning his NFL career at corner, albeit with just seven college starts at the position.

By the way, just to complete the history lesson, Lake was a linebacker at UCLA before he became a safety-turned-cornerback in the NFL.

Q: Potential issues between Harbaugh (hard worker) and Crabtree (never played in preseason)? @mjl84

A: I realize Crabtree has a diva reputation. And his training camp dust-up with Vernon Davis and his half-hearted effort to make a post-interception tackle in the season opener in Seattle only enhanced it. But after a rocky start, Crabtree was praised for his work ethic (at least publicly) by Mike Singletary and Alex Smith during the season.

My crystal ball doesn’t forsee potential issues, but Harbaugh is probably the guy to handle them if they do arise. I’m guessing he got plenty of training in dealing with high-maintenance wideouts during his 15 seasons in the NFL.

Q: If there’s no season, will there be a draft next year? How do they handle the draft order?

A: NFL spokesman Greg Aiello responded via e-mail that the answers to these questions are “to be determined.” I think the NFL will cross that bridge when it comes to it, but obviously hopes to never get there.