True, 4 weeks is not quite accurate, re-injuredd on August 30th, returned to play on October 8th so about 5.5 weeks.I believe Kupp hurt the hammy like 6 or 7 weeks before playingCooper Kupp came back in 4 weeks from his hamstring, looked solid at first and has not looked the same since giving the worst stretch of fantasy production in his whole career.
Dulchich returned after 4 weeks from his hamstring, did not make it a half.
Diontae returned after 5 weeks with his hamstring, like Kupp he looked solid initially and again like Kupp has proceeded to give a stretch of bad games you'd have to go back to his rookie season with Mason Rudolph as his QB to equal.
Friermuth sat out 7 weeks with his various hamstring issues.
Jelani Woods has been out all year with a hamstring he had in camp, and then he recently had an injury to the other hamstring and will never see the field this season.
Just looking at this it sure seems like a return to play in 4-5 weeks has not been going so great. Maybe that's simplistic and there are other things at play with these players, but it's not like the Vikings don't have GPS tracking and all kinds of stuff to have baseline tests for JJ to get an understanding of his health status now vs pre-injury. If they feel the need to take more time it's likely based on info they have.
Which considering how he's looked is only more reason to not put JJ back until they feel like he's ready.