Fantasy Upside
Matt Cassel is a veteran who has had some mild success during his NFL career. Part of the problem is the last year he was even close to being an effective NFL starter was 2010 with Kansas City. But the Bills will likely want a game manager and Cassel can be that. He had nine starts the last two seasons with Minnesota and actually managed to complete 59.6% of his passes. But that might be the best thing we can say about him from a statistical standpoint.
Fantasy Downside
Cassel threw 14 touchdowns in 9 starts over the past two seasons with the Vikings. He accompanied that with 13 interceptions and really looked bad most of the time. Really, Cassel is an NFL backup so the fact the Bills are considering him a starter shows how desperate they are. In other words, Cassel's numbers aren't going to magically get better. In fact, they might get worse.
Bottom Line
Most likely, the Bills quarterback for 2015 will not be a strong fantasy option. Obviously, Buffalo brought in a veteran like Matt Cassel because of their doubt in E.J. Manuel. The Bills aren't publicly dismissing Manuel, but Cassel will have the inside track for the job. No matter who it is, it will be one of the lowest rated starting fantasy quarterbacks in 2015. Unless you have a league where you need three or four quarterbacks on the roster, no reason to have Cassel on your team.