Okay, so if at first that initial list of factors sounds like dodge, duck, dip, dive, and dodge....maybe just keep reading and give it a chance.
I'm going to compare this stuff to baseball terms, because I'm pretty well-versed in that and Moneyball helped spread it to many people.
Efficiency is the #1 stat this guy has determined helps teams be good and win games. Like with on-base % in baseball. It's not a bulk of the overall picture, it's not the only important thing, but if you had to pick one and only one stat, that's it.
SP+ attempts to value that as well as explosiveness, which would be like SLG% in baseball. It's akin to OPS in baseball, this SP+. Yes, Tony Gwynn was great at having a high batting average, but you need some slugging in there, too. Efficiency + explosive plays = OBP + SLG
Efficiency seems to be a few things - yards gained on first down, first downs, and points scored per drive.
Explosiveness would seem to be yards per attempt, long plays, etc.
I assume limiting these on defense is incorporated as well.
It specifies how turnovers and red zone success rate tend to be more random, and I think we mostly agree with that. I'd suggest turnovers are more random, but that's an untested estimate.
Sacks are good (duh) and incorporated here, but something I've noticed in my research is how Georgia under Smart tends not to have great sack totals. Like year after year, it's not really a priority for them, which makes them unique, as everyone else seems to consistently have more. Smart is doing something different when it comes to having great defenses without ebbs and flows in sacks.
So what SP+ is doing is not rewarding big wins and penalizing losses, but simply taking each small piece of a football game (or an at-bat in baseball) and adding/subtracting it to tell the story of how good a team is.
Maybe you don't believe you can take apart and engine 100% and put it back together and call it the same engine, but maybe you can. It's an attempt to remove the inherit bias we all possess, take out as much of the randomness as you can, and to just rate teams on what is.
You can agree with it or not, and we all find issues with it, I'm sure. But those issues we have are probably due to those human feelings and preconceived notions that most every formula tries to eliminate.
