One year after going 4-12, San Francisco went 13-3 and made it to the Super Bowl (ultimately coming up short). Offensive improvement (from 16th in scoring to 4th) and keeping quarterback Jimmy Garoppolo healthy was part of it, but the 49ers defense was the biggest reason for the turnaround.

A year ago, San Francisco had one of the league's worst defenses in both points allowed and takeaways, was outside the top 20 in sacks and defensive touchdowns, and was outside the top 10 against the run, the pass and in total yards allowed. There really wasn't any one area this defense was good at.

Flash forward to 2019, and it was a dramatically changed defense. San Francisco drafted Nick Bosa (pictured), traded for Dee Ford (from Kansas City, as it happens), and signed Kwon Alexander in free agency. The net result was a defense that made a double-digit climb in the rankings in every key defensive area but run defense.

SAN FRANCISCO DEFENSE, ONE YEAR LATER
Category2018Rk2019RkRk+/-
Sacks3722nd485th+17
Interceptions232nd1217th+15
Fumble recoveries528th154th+24
Takeaways732nd276th+26
Defensive TDs123rd55th+18
Points allowed2728th198th+20
Yards allowed34613th2822nd+11
Run defense11314th11317th-3
Pass defense24711th1921st+10

San Francisco's lone defensive weakness can largely be attributed to Alexander being hurt the second half; with him healthy the first eight games, San Francisco allowed nearly 20 fewer rushing yards (122-103) and 5 fewer touchdowns (8-3) then when he was sidelined the last eight games. Alexander returned for the playoffs and this defense was better, albeit not quite good enough in Super Bowl LIV.

--Andy Richardson