Opponent adjustment is perhaps the hardest part of scouting, but it's essential to achieving a meaningful portrait of a player. For now and maybe forever, stats are necessary for understanding a player's competition. Here's a quick look at how Mark Sanchez and Matthew Stafford compare against similar quality defenses.
Note: FEI is a drive based stat and does not separate for run and pass.
Mark Sanchez
Average Opponent Defensive FEI: 50.1
Overall AY/A*: 8.46
Top 20 Opponents: 2
AVG Rank: 16
AY/A: 7.46
Top 30 Opponents: 3
AVG Rank: 19.7
AY/A: 9.54
Matthew Stafford
Average Opponent Defensive FEI**: 37.5
Overall AY/A: 8.19
Top 20 Opponents: 3
AVG Rank: 11
AY/A: 5.25
Without Florida:
AVG Rank: 16
AY/A: 5.90
Top 30 Opponents: 7
AVG Rank: 19.70
AY/A: 6.87
Without Florida:
AVG Rank: 22.83
AV/A: 7.39
Sanchez performed better overall against top competition. Stafford played against much better competition overall. Sanchez is haunted by a single, but substantial and pervasive red flag: Small sample size. He performed light years better against Penn State than he did in any other game, recording a 12.94 adjusted yards per attempt. Both quarterbacks suffered one truly humiliating contest. Stafford's came against the top overall defense in college football: Florida. He averaged only 3.94 A/YA. Sanchez's came against 45th ranked defense Arizona State. He averaged only 2.1 AY/A.
This is a very shallow look, but it is worth noting Stafford played alongside an inferior defense, against better competition, and with much worse overall starting field position.
* Sacks omitted.
** Stats against Georgia Southern omitted.