It turns out that Eric Heitmann, who is likely lost for the season, was a victim of Mike Singletary's infamous nutcracker drill, which felled several starters over the past two seasons. Left tackle Joe Staley told SF Gate that Heitmann's neck injury occurred during one of the nutcracker battles at the start of last year's training camp. Heitmann, 31, had surgery to repair a ruptured disc four weeks ago, and he likely will miss the 2011 season.
The nutcracker, in which two like-sized players try to knock each other backward, was a Singletary favorite, but it quickly drew the ire of players when the coach unveiled it in 2009. The battles left a number of players injured that year, including three potential starters, Patrick Willis (ankle), Tarell Brown (toe) and David Baas (broken foot).
Despite the controversy around the drill, Singletary revised what he insisted was a safer version last year. Still, at least two players, linebacker Derek Walker and Heitmann, were injured in it. At the time, the 49ers referred to Heitmann's injury as a "stinger" -- a nerve injury caused by trauma to the head, neck or shoulder. Shortly thereafter Heitmann suffered a broken leg. He recovered from the fracture but could not shake the neck problems and was placed on injured reserve on Nov. 2.
Singletary insisted on the nutcracker because he said it taught players the importance of leverage, and it was the iconic drill of the coach's tough-guy approach. In 2009 Singletary said he didn't think the drill would cause injuries because the two players facing off didn't take running starts. At the beginning of that training camp, he called it "pretty foolproof."
-- Matt Barrows