Not looking to argue against Moncrief here but these are mostly pretty poor examples for Moncrief. Most of these guys had one or multiple thousand yard, WR1/WR2 fantasy seasons under their belt at this point.
Of those missing it, Welker/Jordy hadn't had an opportunity yet (I was very clear in mentioning I was looking for guys that had opportunities and failed, not guys who hadn't yet received their opportunity). Both were studs as soon as they got a chance to start regularly.
That leaves us with Harrison, who did indeed not break out until his 4th year even though it looks like he was a starter right out of the gate. I don't really remember back that far that well, though his early career was pre-Peyton (whereas Luck has been there for Moncrief's whole career), and each of his first 3 years, while not great, were still far better than Moncrief's career best so far. He is probably the best hope though (right down to the year 3 injury), even without the matching jerseys.