SANTA CLARA, Calif. -- Monday might have been the most event-filled day at 49ers camp this summer.
Center Eric Heitmann fractured his left fibula and was lost for six to eight weeks.
Backup defensive end Kentwan Balmer, a first-round pick in 2008, met with head coach Mike Singletary and was allowed to leave the team for what was labeled "personal reasons," although the reasons may be more professional.
Behind the scenes, Singletary continued to get into the minds and hearts of his players.
The Monday morning practice didn't meet Singletary's high expectations.
"Hump day"' is what he called it, but the 49ers are a franchise trying to get over the hump with hard work, maturity and accountability. Singletary often speaks about how he wants more maturity from his team, and he knows the 49ers have a long way to go.
It's not out of the question for Singletary to keep his team on the field for three hours if the team is clicking during a training camp practice. Things weren't clicking Monday.
Passing was off. Hitting was inconsistent. Focus was spotty. When linebacker Parys Haralson blew up a blocker and crashed into quarterback David Carr, Singletary called the team together on the field and said he was going to cut practice short.
Players said they wanted to finish and they did, words that sounded good to the intense 49ers coach. The 49ers don't have the type of athletes who will dazzle opponents. This team can win by being tougher and more focused than its opponents.
Back to Balmer for a second. It will be interesting to see how Singletary handles this situation.
Balmer missed his third straight day of practice Wednesday -- but this absence was not excused. The team announced that Balmer will be fined for his unexcused absences.
In his third season, the former first-rounder hasn't established his role in the defense and apparently is frustrated. With nose tackle Aubrayo Franklin out of camp in a contract dispute, the 49ers don't have the depth to give up on a lineman with potential. While Balmer sorts out his issues, the 49ers will keep working.
Here are three more observations from 49ers camp.
• Tough offensive line: Finally, the 49ers have an offensive line that fits the personality of their coach. As a player, Singletary was tough, intense and no-nonsense. The additions of Iupati and Davis to the line bring out those qualities.
Iupati is exciting to watch. He's 6-5 and 331 pounds, but Iupati can move. Watching him pull to his right on running plays is a treat. As a pure blocker, he's a mauler. As a pulling guard, he's a battering ram, destroying any defender in front of him.
Once he gets the timing down with Iupati, running back Frank Gore should run even better to his right.
Normally, teams don't like to draft guards 17th or higher in the first round unless they are Steve Hutchinson. Iupati may not be as smooth as Hutchinson was for the Seahawks, but he should make every bit the same impact. The surprise is Davis, a tackle from Rutgers who scared teams away because of what they considered questionable work ethic. Davis has been a model worker for Singletary. Soft-spoken and reserved, Davis worked his way quickly into the starting job at right tackle, where he'll likely play next to Chilo Rachal, who has the edge in beating out Adam Snyder for the right guard job.
The 49ers have a nasty edge to their blocking style. Davis has excellent feet. Rachal is a mauling type of blocker. David Baas will replace the injured Heitmann at center, giving the 49ers four starting blockers weighing between 323 and 331 pounds. Left tackle Joe Staley is the lightest on this powerful line at 315.
• What will offense feature? Offensive coordinator Jimmy Raye still is sorting out whether he wants the offense to feature the power running attack or the three-receiver spread out of shotgun that works better for quarterback Alex Smith.
It's pretty evident from watching practice that the 49ers will lean to the power running game more and use the spread offense only on traditional passing downs. The makeup of the offensive line probably points the offense more to the power running attack. Having two rookies on the line could make it tricky to feature more passing.
Even though Smith has more weapons at wide receiver with Michael Crabtree in his first training camp and a deep threat in Ted Ginn Jr., the talent on the team seems to favor the running attack. The 49ers are four-deep in power runners: Gore, Glen Coffee, sixth-round pick Anthony Dixon and Michael Robinson. Raye can present a formidable three-receiver package with Crabtree in the slot, Josh Morgan at flanker and Ginn at split end, but Smith, in his sixth season, isn't the best at pinpointing throws that hit receivers in stride.
Sure, he's good at getting the ball to the receivers, but he's not Peyton Manning or Tom Brady when it comes to getting the ball where receivers prefer. The good news is the passing offense can get into spread sets in the fourth quarter when behind and cause problems for defenses.
Clements looks good: It was good to see cornerback Nate Clements back on the field and making plays. Clements, the league's first $10 million-a-year cornerback, struggled last season both on and off the field. Now, he's back on the field with Shawntae Spencer securing the corners for Singletary's defense. What's nice about this defense is that it's in its third season together and roles are defined. Singletary knows his 3-4 defense isn't like most. Normally, 3-4 defensive coaches try to load the front seven with big players so that the defensive linemen wrestle blockers and linebackers are big enough to overpower offenses.
Singletary has a relatively light 3-4 defense that former head coach Mike Nolan converted from a 4-3 scheme. Singletary takes advantage of the defense's quickness to occasionally let linemen shoot through one gap to make plays in the backfield. Inside linebacker Patrick Willis is clearly one of the best defensive players in the league and the line does enough to free him up to make plays.
The team can't afford to have Franklin hold out into the regular season even though Ricky Jean-Francois is doing a nice job filling in for him at nose tackle. From a personnel standpoint, the 49ers didn't need to add much to the defense this offseason. Safety Taylor Mays, the second-round choice, is trying to pick up the scheme. Third-rounder NaVorro Bowman is a solid inside linebacker. Free-agent corner Will James could help with some matchups against bigger receivers when called upon.
John Clayton, a recipient of the Pro Football Hall of Fame's McCann Award for distinguished reporting, is a senior writer for ESPN.com.