Stafford has Megatron to win jump balls all day, Freeman is playing like crap, Dalton has had a cupcake schedule and Newton is 2-6. All of them would be better with a strong running game, same as Sanchez.
Although I think the continuity angle has been a bit blown out of proportion, in regards to Mark.....I think the smartest way to go would be to bring back Plaxico next year, and then take advantage of the dearth of WR's available in this upcoming draft, to snag a long term replacement. Then we'd have all of Holmes, Kerley, (potentially) Keller, and a young WR to grow with Mark for the foreseeable future.
On that whole list, who had accomplished more in his first 2-1/2 years in the NFL? You could argue a couple on the list, but Mark has had way more success than most.