Stacy and the Rams RB situation presents an interesting conundrum in fantasy. Last year, Stacy was absolutely the lead dog, getting the majority of the carries and leading the team in all major statistical categories for the position. Owners that drafted him, or picked him up early in the waiver process were rewarded with one of the best fantasy seasons at the position relative to the amount of games he was "the guy".
But there are lots of things to look at to suggest that Stacy is going to have a rough 2nd year, at least from a pure fantasy perspective. The first is the addition of Tre Mason. Mason, a heisman trophy finalist, has more of a pedigree than Stacy did, and so far has shown great burst on some runs, albeit against lesser talent. Benny Cunningham, undrafted last year, has a year of NFL experience under his belt and looks the part of "bruiser" that Fisher covets: big, physical dominating physique, and runs behind his pads better than anyone on the roster. Not to mention the Rams feature a very fragile Rodger Saffold at right guard and a rookie LT playing guard for the first time in years on the left side, and a center situation that is much more fluid than many care to admit point to the Rams experiencing (some) difficulty on the interior line, and so far the offensive line has lacked any notable surge on running plays early in the preseason.
The main thing that points to a regression for Stacy, however, is the possibility of Sam Bradford playing 16 games, and of having a more talented back up in case Sam goes down again in Hill. Necessity dictated a power running game come about simply because the Rams did not have the talent to throw the ball successfully. That has changed in a BIG way this year, with Sam looking the part of talented, poised pocket passer and the emergence of WRs who either were not difference makers or are new to the roster.
A crowded backfield, question marks at the "running game" positions on the offensive line, and a change in philosophy from the second half of last season all suggest that Stacy is headed for a decline from a numbers standpoint.