With how the defense was improving you'd think he would want to stay ... unless it was improving because Flores stepped in. Maybe we will find out sooner or later.
The defense wasn't really improving near the end of the season. It had improved quite a bit from the first 2 weeks which were total blowouts, but from weeks 3 through the end of the season it was pretty consistently bad having only a few games that were a little better but against typically weaker teams like the Redskins, Jets and Colts. The defense reached it's peak about week 9 when they only gave up 12 points to the Colts, but it was the Colts so you have to take that with a grain of salt. They were still giving up over a 1/2 point per play for most of the year even the last 3 games.
Here's the stats for the defense for the year. Other then the first 2 weeks which they were just blown out, they were pretty consistently bad, giving up an average of 28 points per game. That's not good and not really that far from the 24 they gave up to the Patriots, it's just that weeks 1 and 2 were so bad it made weeks 3 through 14 seem better by comparison.
GM TEAM YDS CMP ATT AVG RSH ATT AVG TOT PLYS PTS AVG PTS/GM
1 Ravens 378 23 26 14.5 265 46 5.8 643 69 59 0.9 59.0
2 Patriots 255 20 28 9.1 124 35 3.5 379 55 43 0.8 51.0
3 Cowboys 241 19 32 7.5 235 34 6.9 476 53 31 0.6 44.3
4 Chargers 311 25 31 10.0 79 33 2.4 390 58 30 0.5 40.8
5 Redskins 166 13 25 6.6 145 33 4.4 311 46 17 0.4 36.0
6 Bills 188 16 26 7.2 117 23 5.1 305 39 31 0.8 35.2
7 Steelers 236 20 36 6.6 158 29 5.4 394 49 27 0.6 34.0
8 Jets 238 27 39 6.1 83 21 4.0 321 48 18 0.4 32.0
9 Colts 191 18 39 4.9 109 29 3.8 300 47 12 0.3 29.8
10 Bills 256 21 33 7.8 168 34 4.9 424 55 37 0.7 30.5
11 Browns 320 24 34 9.4 147 32 4.6 467 56 41 0.7 31.5
12 Eagles 294 28 46 6.4 92 19 4.8 386 47 31 0.7 31.4
13 Jets 262 20 36 7.3 112 32 3.5 374 52 22 0.4 30.7
14 Giants 274 21 29 9.4 138 33 4.2 412 54 36 0.7 31.1
15 Bengals 371 33 56 6.6 59 25 2.4 430 58 35 0.6 31.3
16 Patriots 217 16 29 7.5 135 27 5.0 352 43 24 0.6 30.9
TOT 4198 344 545 7.7 2166 485 4.5 6364 829 494 0.6 30.9
What was improving was the offense under Fitzpatrick. He played some of the best football he's ever played in the last half of the season which is the reason for the better record in the 2nd half of the season. Don't forget that Fitzpatrick did not play well the first couple of weeks which is why he was benched in favor of Rosen who did even worse and Fitzpatrick was put back in. By the end of the year the offense was doing well enough to keep us in games, but the defense really wasn't looking that much better then it looked in weeks 3 and 4.