Fisher has never had an offense that scored more than 42 TDs (1999). He's only had 4 that have scored more than 38 or more (99, 02, 03 and 04). His highest offensive output (TD & FG = PPG) was 22.3 in 1999. He's only had 4 years when his offense averaged 21 points or more (99, 02, 03 and 08 ). That's the bad news. In 20 full seasons, his defense/special teams have averaged 4.5 TDs per year. They scored less than 4 TD just 6 times and have scored more than 4 seven times (3 out of 4 with the Rams). That's an additional 1.9 points per game, every game, every year. So his defense is more consistent than we could hope his offense to be. But that's just defensive scores. That is not including a TD or FG scored by the offense by virtue of the defense setting them up in a good scoring position. So, practically any offense in the NFL with a Fisher designed defense is going to score about 2 more PPG. Doesn't sound like a lot but when 25% of games are decided by 3 points or less each year, it's considerable.
Having said that here's some more bad news. His offensive theory (if there is such a thing with Fisher) is obviously run, run and run some more. Only once in 20 years as a head coach has his offense had 30 TD passes (2003). They went 12-4. He's had 3 teams go 13-3 (99, 00 and 08) and the TD pass total was 23, 18 and 13 respectively. Twice he's achieved a 13 win season with less than 20 TD passes. I wouldn't expect to win 13 games if someone told me 'your team isn't going to have 19 TD passes this year. It's true you can't count on non offensive scores year in and year out but Fisher's defenses and special teams seem to always contribute to the scoring. Not once in 20 years of coaching has he been blanked in non-offensive scores and only three times has he had less than 3. But we're talking about offense here.
Many believe he lost his job in Tennessee because of Vince Young. And that may be true. He made the playoffs with VY in 2007 (10-6) but that team finished 3rd in the division. The next year with Kerry Collins under center for all but 1 game, they won the division (13-3). Some thought Carson Wentz was the prototype Fisher QB, in the mold of Steve McNair. And I've read some random opinions that suggested Fisher wanted Wentz. Who knows if that's true? I believe that Goff may end up being the most talented QB as a pure passer that Fisher will ever have, including McNair. But will he turn him loose? The saying is 'a leopard can't change his spots' but I believe if Goff becomes that guy, Fisher will take full advantage of that talent. And if he does, we may be in for a treat with both Gurley AND Goff....a reprieve for Ram fans from the mid 70's and 80's when we always had a horse of a RB but only had a good QB for a couple of seasons with Ferragamo. And for 3 of his seasons, that horse was Wendell Tyler.
EDIT:
A little more research on Fisher and QBs, he has been a head coach for 20 full seasons and in just 4 of them has he had the same guy start all 16 games (97, 98, 02 and 12). His lifetime regular season winning percentage is .519.9. In seasons where he's had a 16 game starter his winning percentage is .546. In seasons where he hasn't had a 16 game starter his percentage is .513. Well here's hoping he doesn't have a 16 game starter this season,
.