I know very little about NFL, although I really enjoy watching it, but I find it amazing that outside of the QB individual players can make such a massive difference to the fortunes of a team. With the QB it makes sense, it's clearly a very hard position to play and you need outrageous ability in all sorts of different ways. But when the likes of Hopkins gets injured and your whole offence goes to pot... how is it that a position that is seemingly mostly about being a physical specimen and having great hand eye coordination can see such colossal levels between players such that the backups for Hopkins can't do close to what he does. This applies to loads of positions. Some players are just WAY better at rushing the passer than others, but why? You'd of thought, from an ignorant lay person's perspective, that it's basically all down to physical attributes, but it clearly isn't, because the physical differences between a Hopkins and whoever has replaced him is probably tiny, but the difference in outcome is massive. I guess there are skill elements of being a receiver that I just don't see or understand but even these must be pretty small and in lots of ways, 'in the head', rather than much obvious technical superiority.
Good observations. There sometimes is a minimal drop-off but sometimes a major one (that can be amplified and taken advantage of). Some of the gap could come down to a few areas:
1. Technical aspects
-While the gap may not be massive, there's a difference in ability to run clean routes, run block, etc that goes beyond the physical ability and catching ability. Some guys have the physical capabilities and are good catchers of the ball but may struggle in other aspects that impact their playing time and ability to get open to make those plays.
2. Familiarity/Timing
-This is feeding into the mental aspects of the game you mentioned. Familiarity with the QB, offensive play calling, scheme, adjustments, etc. Receivers that start and are part of the first-team reps get that comfort with quarterbacks. Backups may not have that down. You'll see miscommunications, poor timing/reads, etc on the field. There's also the trust factor. If the backup receiver is just a little less competent in various aspects, as a QB (and as the play caller), you may want to look at other targets, and the entire gameplan may change. The defense will also respond accordingly, so the loss of a player like Hopkins can have a knock-on effect.
3. Roles
-Some players may have a similar position to others but will have preferences where they line up and operate on the field. Receivers are a good example of some being more comfortable operating on the outside and others being more comfortable inside. So you could have the depth, but it's hard to have top second options for all specific roles. This will often go hand in hand with the technical aspects but of course physicality as well. The combination of size/speed does reach a level for these roles that even other physically-gifted backups can't reach.
With the salary cap in place, teams can't really afford to have top-notch players all around for depth. They can try to replicate the best they can (e.g. have a receiver that has at least can reach a level of physical and technical ability that is close to Hopkins) or shift the gameplan altogether to cover for his absence (which can be easy or hard depending on personnel, coaching, time to prep, etc).
For football analogy, I think the Trent example is a great one. There are some ridiculously good attacking fullbacks in modern football, yet his ability and our style of play really is quite unique, and there's very little chance any backup can operate like he can (even if stylistically and physically players like Neco are able deputies, you still lose a lot). It doesn't mean we can't win matches without him, but in some moments/matches, it could prove decisive since he's so important to how we play.
