I have tom brady as a keeper in my fantasy league. how much do you think stallworth will help him will he be a branch or better? or worse?
Your question is more complicated than it appears.
First of all, factor in Stallworth's injury history and make a guess at how many games you think he will play. Personally I'll go with 14.
From there, keep in mind that the benefit of Stallworth is seen not necessarilly in his numbers, nor soley in Brady's. It's in the offense in general and the W/L column.
In effect having Stallworth on the field prevents defenses from collapsing on the rest of the offense the way the did last year.
That means that the YPC of most of the receiving threats goes up. I would look for Watson's YPC to go up by a few yards (if I played Fantasy football I'd grab him), as well as the other WRs that are on the field most often.
Pass catching RBs will be more of an option and their yards on the ground and after the short catches might improve by the fact that safeties are in the backfield keeping an eye on Stallworth.
If things go according to plan though, Brady and his offense, in part thanks to Stallworth's presence, will be able to build a big lead and hold onto by running the ball. Brady will throw deep to Stallworth enough to keep the deep threat valid at all times, but there will be no reason to take too many risks with the longball beyond that - and they will have the ability to spread the passes around as they always prefer to.
So if you look at Brady's SB year numbers you'll see its nothing to get overly excited about - but the offense in general will be good - the defnese will be great, and the Win Loss record will hopefully be enough to give us a bye and home field advantage when the "real" season starts in January (but we do play a tougher schedule this year than compared to last by the looks of it - so getting back to 12 wins will be a challenge).
So again, as of now, take Watson and Maroney. They'd be the biggest benefactors statiscally beyond our Wins and Losses.