What Fins receiver is better than Welker?
Welker is a SLOT RECEIVER. That's a different position than WIDE RECEIVER, although both are called wide receivers.
Similarly, a pass catching tight end is not a receiver, even though they sometimes lead their teams in catches.
To be a really good slot receiver requires a totally different set of skills than being a "true" wide out.
So when you ask what receiver we have who is better than Welker, I'd say "that depends". He's a better SLOT receiver than anyone we have, sure (although Bess could turn out to be quite good as well), but if he had to line up wide on every play, I'd say we have SEVERAL that are better than he is.
Welker is thriving in New England because they like to get rid of the ball quickly and have GREAT wide outs. That leaves him with coverage mismatch and the result is lots of slants and other underneath stuff.
A slot receiver has to be tough and smart enough to read coverage. There are a lot more reads to be made as a slot receiver compared to a wide out. It's simply a different skill set.
Welker might just be the best slot receiver in the league. It'll be interesting to see what happens if he gets a mega-contract somewhere though, and they stick him out wide as a #1.