Welker is 5'9, Manning is 6'5 according to ESPN. Welker is awfully small for playing in the NFL, but almost perfect for a slot WR with his quickness and agility, he can weasel his way to getting some serious YAC, like in one of his TD's with the spin and dash for the endzone.
Allso, @ the suggestion about changing to another thread: why? There are threads much longer than this one out there, we aren't cluttering anything or bogging people down unless they are masochists and try and read through the whole thing.