Rainey is never a great play. He's at best a desperation play that could potentially pay off. He has been awful as a starter. He's rushed for better than 3.7ypc in just 2 of his 8 career starts, 2nd worst in the entire NFL. And that was with no one behind him to bench him for if he starts slow or loses an early fumble. He's as likely to have 6 carries for 7 yards with a fumble and then sit the rest of the game as he is to go for 100 yards.
The Browns are a great matchup, so there's hope and it could pay off, but the Falcons were too so there are certainly no guarantees with this guy.
rainey has started two games this year and in both hes been a good to great play so i have no clue what you are talking about?
It's easy to forget that Rainey had negative points going into the 4th quarter of that Atlanta game and racked up some major garbage time stats while trailing by 50 points. It's unlikely that the Browns will hang 50 on Tampa and equally unlikely that Rainey would get those looks now anyway (what better time to try out Sims?).
Here are Rainey's 8 career starts.
18-35, 1.9ypc (0-0 rec)
17-63, 3.7ypc (2-8 rec)
22-127, 5.8ypc (4- -4 rec)
11-27, 2.5ypc (1-3 rec)
20-37, 1.9ypc (1-4 rec)
11-35, 3.2ypc (1-1 rec)
22-144, 6.5ypc (3-30 rec)
11-41, 3.7ypc (7-64 rec) (had sub 1.0 ypc and negative fantasy points late in the game before some serious garbage time).
Rainey's biggest concern in this game is not just that he's a poor runner, but also that he's weak in the areas where rookies generally struggle (IE things that would normally keep Sims on the bench behind him). Rainey is a below average runner who can't pass block and has poor ball security. He's a good receiver, but so Is Sims and Sims, despite being a rookie that has never played a game, may already be better than Rainey at pass blocking and holding onto the ball.
He's been a complete, useless dud in 5 of his 8 career starts. In one other one he racked up some points while down 50 in a game that otherwise would have been his biggest dud yet. He may be a decent upside play as a starting running back who's had a few good games before against a really bad run defense, but to call a guy that's more likely to throw up three points than 20 a "great" start is very optimistic. Rainey wouldn't be a "great" start against Vanderbilt.