Borrowed this from another site:

2016 Alabama Defense
Total Defense = 2nd at 261.8 Yds per game
Rush Defense = 1st at 63.9 Yds per game
Pass Defense = 24th at 197.9 Yds per game
Pass Eff Def = 9th at 106.47 rating
Scoring Defense = 1st at 13.0 PPG

Lost to the NFL Draft on Defense....

Humphrey, Marlon CB 6'0" 197 Pick 16, Round 1 (16) Ravens
Allen, Jonathan DE 6'3" 286 Pick 17, Round 1 (17) Redskins
Foster, Reuben LB 6'0" 229 Pick 31, Round 1 (31) 49ers
Anderson, Ryan OLB 6'2" 253 Pick 17, Round 2 (49) Redskins
Tomlinson, Dalvin DT 6'3" 310 Pick 23, Round 2 (55) Giants
Williams, Tim OLB 6'3" 244 Pick 14, Round 3 (78) Ravens
Jackson, Eddie S 6'0" 201 Pick 5, Round 4 (112) Bears

BTW, 5 of those guys started as Rookies.

So, what does Nick Saban have to contend with in 2017?

1 - Replace SEVEN NFL draft picks.
2 - Starters Christian Miller, Terrell Lewis lost for the rest of the regular season after the FSU Game.
3. Starter Rashaan Evans torn groin muscle, out/limited for 6 games.
4. Co-Starter Anfernee Jennings lost for half the season with ankle injury. Also missed GA game.
5. Starter Shaun Dion Hamilton lost for the season during LSU game.
6. Hootie Jones lost for season rest of season in Auburn game.
7. Mack Wilson injured all season.
8. De'Shaun Hand injured versus Ole Miss.

The list goes on and one. Worst season of injuries on Alabama's defense I can ever remember, and I have been following Bama since 1971.

Now for the amazing part. How badly did this unit perform in 2017?

2017 Alabama Defense
Total Defense = 1st at 260.4 Yds per game
Rush Defense = 1st at 94.7 Yds per game
Pass Defense = 6th at 165.7 Yds per game
Pass Eff Def = 2nd at 96.78 rating
Scoring Defense = 1st at 11.9 PPG

The 2017 Alabama Defense put up better numbers in 3 of the 4 main defensive categories than the 2016 Defense put up. The only one they didn't exceed was Rushing Defense.

The above set of of facts, by itself, should have secured a unanimous Coach of the Year award for Nick Saban.