I'll take your word for it, but it sounds like bullshit to me.
If he was trying to phase out Welker, it proves Belicheck was a dumbass handling it. Who gives a shit if the guy produces out of his mind and wants to get paid for it the following year? He's still on your team, and is better than Edelman. You are still paying him to play that year. So you are telling me that want to phase out a paid asset, for a guy that is making less and is not as productive? Silly.
I'd take the answer of McD playing around with different play sets or even a little slap for 2 games. A full on phase out doesn't make sense, even with injuries. He was too valuable in that offense.