First off, Alexander probably should of been in the top 2...
That being said the All-Pro list has a problem... they FINALLY took FB out and added a 3rd WR (which I really think should be WR/TE flex but close enough)
But they failed to make the same correction on defense, of taking a KB out and adding a 5th DB (CB/S flex), which most likely would be a 3rd CB over 3rd Safety.
With a few exceptions, teams are 50% of the time in 4-2 nickel defenses with 2 interior DL, 2 Edge Rushers, 2 LBs, 2 Safety, 2 CBs and one flex position which normally a DB that is either playing nickel CB or LB/S tweener role.
Basically they need to make that last position on both sides of the ball, a flex position... and the way the NFL is running right now, the last offensive spot should be a WR/TE and the last defensive spot should be a CB/S or maybe, just maybe a coverage LB.
But I think Alexander should of been among the top 2 CBs (and he graded better than the other CBs based on PFF) ... but even if not, should of make it over the 3rd LB.