Lets look at each trade individually :
Welker for a 2nd round pick(Samson Satele) and a 7th round pick(Abraham Wright):
Lets first point out the most obvious thing about this trade. The 7th round pick, Wright, amounted to nothing and is no longer in the NFL. Though, that shouldn't hit anybody as a HUGE surprise, since picks in the 7th round are rarely succesful. Occasionally will you hit gold on a starter or find a decent backup. Most don't last long and just fizzle out.
Samson Satele came in last season and became an instant starter at center. He has the potential to be the starting center for this team for the next decade. Without a good line in the NFL, your running game and passing game will struggle, no matter who you have at the skill positions.
I truely believe Wes Welker would not have had a huge year like he did if remained with the Dolphins. The fact that Welker had the best QB in the NFL throwing to him and that fact that Randy Moss was also on the field made things easy for him. You put Welker on any other team in the league besides the Patriots, and I think he is an average receiver who gets maybe 50 catches in the season.
Despite Wright fizzling out way to early, I think Miami made out better on this trade. They got a guy who will be a fixture on the offensive line for many many years.
Chris Chambers for a 2nd round pick(Chad Henne):
I liked Chambers and thought he made the most amazing catches. However, he would also drop the easy ones. I also hated the fact that everytime he dropped a ball or just didn't give that extra effort he would raise his hand in the air and shake his wrist looking for a flag.
He is a very good receiver and will be a big part of San Diego's success. He will never be an elite receiver, but he will be a very good one. San Diego is on the verge of a trip to the Super Bowl, we are rebuilding. Chambers is 30 years old this season, so by the time we will be up there for a trip to a possible Super Bowl, he will be 33 or 34 years old.
Chad Henne has showed great promise in the preseason and training camp. I think he will prove to be the next long term starter at QB for the Dolphins.
So, in conclusion, I think both trades were good for the future of this franchise.