Sounds similar to the Tate explanation a couple of years ago
It does sound similar, I'll give you that. In all of those players' defense (Vereen, Brace, and Tate) I would say the exact same thing all over again if their situations came up. You have to take each separate situation into account, and just b/c one or more of those players at other positions didn't work out does not mean that Vereen is necessarily going to be a 'bust.'
The difference will likely be the fact that one or more of the RB's will be gone next yr (I am assuming Faulk, and possibly Green-Ellis) and that should automatically step Vereen up in the depth charts.
The hopefullness of a full off-season without injury would add to that too, of course. RB isn't as hard of a position to learn here as running routes in this complicated offense (Tate), or trying to learn the nuances of a Bill Belichick coached defense (Brace).
In the case of Tate, he had a lot more going on (or in his case, NOT going on). When you don't run routes particularly well, have one of the NFL's best WR's in front of you catching balls, and the team changes their offense into a 2 TE set on 70% of the plays, that tends to set you back.
There's also the fact that Tate had other guys contributing on the team more, which made his departure necessary. Edelman was an obvious choice over Tate (at least in my opinion), and Ochocinco was a highly touted free agent with experience and a big contract coming in.
In the end, the #1 reason for his departure was likely a combination of all of the above, added in with his poor chemistry with Brady.
I really don't see the similarities (at all) with the positions, due to the players in front of them, the expectations that were dealing with, and Vereen's having been a rookie with a nagging injury in a labor disputed off-season.