We don't have a designated short yardage RB. Sometimes it's Jamal, sometimes it's Lasike, sometimes it Brown, but most of the time Hill ends up running in short yardage.
And Lasike IS a big yardage guy. Lasike was our most efficient RB against the best defenses we played: @Wisc - 7.2 ypc, @ND - 25 ypc, and 9 yards in his one carry against Wash (compared to Jamal @ 2.6/2.4/5.4 in those 3 games).
Lasike is very agile for his size and especially for someone as strong as he is. He is a fantastic blocker @ 230lbs so why ask him to gain even more weight when that will most likely make him a less effective runner?