i like the idea and i also like your trading concept, i think that's what trade is about, benefit both team
Fitzpatrick is a rising star but obviously not top 5 QB yet
BUF is extremely strong this year with Fitzpatrick, F.Jackson and S.Johnson, and should keep Fitzpatrick's production up to par with other top QB, maybe not Brees, Rodger and Brady tier, but should be at least up to Romo tier.
Bowe is having a bad season, in fact, whole KC is having a bad season, and Fitzgerald is doing decent with Kolb (must say i am a little surprised), so obviously it's a huge upgrade on WR
Foster is late gamer, meaning if you can hold your rank high enough before Foster recover, then it's definitely the RB you want keep and will help you win play-off, on the other hand, Tolbert has been doing well and is very decent RB2, Foster's value goes down (injury+Tate's good performance) and Tolbert's value goes up, therefore they are pretty even right now (Foster should become more valuable as season goes)
Fitzgerald downgrade to Lloyd is not that big of a deal if Lloyd play up to his projection value, however i am just worry your RB might be a little weak as season move on, Bradshaw didn't show much yet, Greene is not looking good, Helu still fighting for his RB1 position with Hightower, and Tate lose his value as Foster recover.
you are really rely on Tolbert/Best to cover your RB production.
After all, being 6pt passing TD, upgrade to Rodger is clearing nice and seeing your WR can handle the lost of Fitzgerald, this trade should improve your team, and other team got huge improvement on his WR that's enough to cover his QB downgrade, also, you never know how well can Fitzpatrick do.
acceptable downgrade on WR, lost possible play-off star RB but grabbed decent RB2 for better early season matchup, nice upgrade on QB. Other team downgraded on QB, lost decent RB but take chance of having play-off star RB, and big upgrade on WR
i think it's fair and win-win trade, good job, matter in fact, if we strictly talking about trade and not looking at your roster, you are giving slight more than what other team is giving you back.