The Lions' top player for fantasy football is a tossup between receivers Roy Williams and Calvin Johnson. Although Johnson didn't exactly live up to expectations last season, my feeling is that he will be better than Williams in 2008. Johnson's development last year was greatly hampered by a back injury he suffered early on in the season. The injury never really went away and he only got back to 100% health in the offseason.
During the preseason it seemed like Jon Kitna liked throwing the ball to C.J. more than Roy Williams and he did it effectively. The preseason doesn't exactly mean a whole lot, but if it's even the slightest indication of what's to come then Calvin Johnson will become an elite NFL receiver. Between his size and speed, there are very few corners that will be able to match-up well with Megatron, as Roy Williams calls him.
Rookie Kevin Smith has already won the starting job at running back for the Lions and should be a solid pickup for any fantasy player out there. The Lions running game is going to take time as their offensive line struggled greatly in the preseason, but Smith can make plays out of nothing, which is good news for a Lions running back. Smith's combination of speed and power, along with his juking abilities, makes it very hard for defenders to tackle him.
Early on I don't think Smith would be a player you would want starting on your fantasy team, but if the Lions' offensive line can improve as time goes by then he could step into a starting role. I view him as a great running back to have for depth reasons and someone that has great upside.