I respect your posts and your logic, but while well written, this doesn't hold up to scrutiny.
1. By this logic it should be the center on the best team - without the center there would be a fumble on every play and the QB would contribute only fumble recoveries and negative sack yardage. And there is no universe in which a WR could ever get the award, even if he took screens to the house 15 times a game, because those stats would collect to the QB. When you're looking at the impact of the stats, you're not simply subtracting those stats! The counterfactual is not taking the player away or replacing him with a toddler - you're replacing him with an average player. Henry's performance is significantly farther removed from an average player than any QB this season.
2. I disagree. Replace Brady with an average QB and the Bucs are still a playoff team. Replace Henry with an average running back, and see how far the Tannehill passing attack takes you. The last part of this is actually your stats argument from #1 above. Even with thay, I'd argue that a decent percentage of Tannehill's passing yards and TDs are attributable to Henry's presence.
3. We didn't see these Bucs without Brady. We saw the Bucs without Brady and all the other guys they signed in that off-season. It's why people joke about Brady joining an all-star team.
4. Why are teams adjusting their rosters and how defenses are built to take away the long pass? Because there are such a large number of QBs who can beat you with the deep pass. If you didn't plan your roster around it, you couldn't make the playoffs. But we're not having an award for changing the game as a whole - and if we were it couldn't be attributable to one player. By nature it's that there are a growing number of the species that you're worried about stopping. You don't plan your roster and defensive philosophy around one singular talent because the idea of team building is to build something that gets enough wins to get to the playoffs, and from there take each game as it comes. But by this argument, the award is for the player who forces teams to adjust most THIS YEAR.
5. You're right, teams are built to stop the long pass. Therefore, when they come up against the Bucs or Chiefs in the playoffs, where one game takes all, they adjust much, MUCH less to account for Brady or Mahomes than they do for Henry. In a playoff game, teams have to change everything they're doing to switch their focus away from defending the deep ball at all costs, and to stop the run. The player that forces teams to change what they are doing is Henry.
Thanks for the response! While I disagree I appreciate the discussion. Broke down your reply for easier response.
1. I agree, there is no universe in which a WR could win MVP by that logic and those metrics - likely why we haven't seen a WR win MVP since, well, ever. As far as the "replacement level player", we can all agree if your starting QB or RB comes out, it's not the 16th best QB or RB stepping in. On average, it'll be about the 48th best. You don't replace Brady with Justin Herbert, you replace him with Blaine Gabbert. Which, we've seen him come in during games. It's not great. So as long as we're careful about how we're talking about what an "average player" is, I'm all in. The trouble is, with Henry going out, you wouldn't replace him with one player, you'd replace him with multiple. His most impressive attribute is his durability. Y/A, he's at 4.6, tied with Damien Harris, and way below Lamar Jackson (6.3) or Ryan Tannehill (6.6), but more importantly other RBs like Nick Chubb (5.8) and Kareem Hunt (5.2) on the Browns. Combine those two and you're at 884 yards and 9 TDs on 154 attempts vs Henry's 869 yards and 10 TDs on 191 attempts. It's not that he's performing at a level which is above anything we're seeing This Year even, it's just that he doesn't have to come out, and that's rare these days. However, a QB, you don't have that option. Durability is normally not the concern in the first place, it's performance, and Blaine Gabbert and Kyle Trask splitting the reps isn't going to help.
2. The Bucs had an above average QB in Jameis Winston, they were not a playoff team. And I know, I know, 'they had the worst QB in the NFL by the amount of INTs thrown' is one way to look at it, but by that logic Mahomes is the worst QB in the NFL right now and I don't think anyone buys that. Replacing Henry with the 48th best RB and we're looking at a Latavius Murray type, whom across 191 attempts by his Y/A would produce 687 yards instead of 869. A dropoff, for sure, (about 30 yards per game) but hardly insurmountable. The whole reason you see the RBBC across the NFL is because it works, you saw the death of the feature back not because no one could do it but because it wasn't needed, and it was better to have multiple RBs still healthy and ready for the playoffs than one person who had 400+ attempts throughout the year who was at best banged up and at worst unavailable come playoff time.
3. The main other people they picked up were AB and Gronk, both of whom have been out for a couple of weeks now. Also Leonard Fournette, who is splitting reps with Ronald Jones so they have two good RBs instead of one. I get the joke, but it's not accurate.
4. I agree with this entirely, which is also why Lamar Jackson wouldn't be my MVP pick, I've just seen the argument and seen it danced around.
5. The thing is, they're built to stop the pass not the run for a reason. They're not coming out of 2 high when the Chiefs are running the ball (at 4.7 YPC) because Mahomes, even playing as he is, is throwing for 7.6 Yards / Attempt. Any given play, Henry can run it, for on average 4.6 yards, or Tannehill can throw it, for on average 6.8 yards. The threat of a run is just not equal to the threat of a pass.
I get it, Henry is putting up gaudy total yards compared to his peer group, so the media is excited about him. When Shaun Alexander won the MVP in 2005 with 1880 yards and 28 TDs you had Tiki Barber and Larry Johnson right behind him, at 1860 yards and 9 TDs and 1750 yards and 20 TDs respectively. Now, if everything keeps going as is through the rest of the season you'll have Derrick Henry at 2k yards and 2nd place will be like 1300. It's not a "most durable player" award though, and in my opinion he's not even the most valuable player on his team, never mind the NFL. RBs skillsets are easier to come by, it's more acceptable if they're not elite, in most cases you just need them to be good enough to allow play action passes to be effective. Henry isn't doing anything we haven't before, just something we haven't seen lately, and we haven't seen it for a reason. Just MHO of course but that's how I see it.