If Garcon was already in your starting lineup. I'd say do this trade in a heartbeat, but you do already have 3 fairly solid WRs. But a 4th isn't a bad thing...
I think I would still pull the trigger on this trade actually. But it really doesn't solve a whole lot for you.
Your biggest problem is starting Russell Wilson every week. He has not been good for fantasy. There has got to be a better QB on FAs right now? Fitzpatrick? Dalton? Ponder? I'd even go with Hasselbeck or Bradford. Even Kolb is probably a better bet for fantasy, as I think this week was an blip on the radar for the Arizona Offensive line. viewtopic.php?t=524497
Edit: So yes, I see now that Garcon is in your starting lineup as your flex. So yes. I would do this trade for sure. Bowe is a clear upgrade and I don't think Martin is really a downgrade from Mathews very much if at all.