Football can be a cruel, heartbreaking sport.Consider the case of Ian Williams.During last summer's training camp and exhibition season, the 49ers' defensive lineman – in his third pro season after being an undrafted free agent from Notre Dame – finally had a chance to win a starting job with the departure of veteran nose tackle Isaac Sopoaga.Williams outperformed veteran Glenn Dorsey, earned the starting job and played very well in a season-opening victory over the Green Bay Packers. Niners linebacker Patrick Willis used terms such as "amazing" and "unbelievable" to describe Williams' play.But in Game 2 his season came to an early end when he suffered a broken left fibula and ligament damage when he was cut-blocked by Seattle guard J.R. Sweezy.Dorsey then stepped into the starting spot and played very well, cementing his status going into this 49ers training camp, which will have its first practice Thursday.Williams said it was hard to be sidelined last season and watch the team go on without him all the way to the NFC Championship Game. But Williams was confident he would be ready by the opening of training camp.Now, his future looks a bit more cloudy. Last week,...