The secondary looks like this in September:

CB - Talib

CB - Rogers-Cromartie

FS - McCourty

SS - Pollard

If they pulled this off, would anyone really miss Welker that much? This would make them a top 10 defense easily, and they'd still be a top 10 offense.

I'm not suggesting this is exactly what is going to happen, but don't be surprised to see them re-sign Talib and get some more help in the secondary, which would include another corner and a hard-hitting safety.