It's a little unsettling to look to the Jags as a positive example, but 3 things are interesting.
1) Many posters here blame the lack of pass rush for the Bucs passing troubles. And that's spot on. But "build from the trenches" can be overblown. It's no accident that all the top pressuring teams have elite cover players as well. To have an effective pass rush you HAVE to have both. And the Jags have two of the top CBs in Buoye and Ramsey.
And it's not just the pass rush helping these CBs. In more in-depth stats like contested catches, etc. these CBs are playing at a very high level. Even when the ball is being thrown at them, they're making great plays and shutting down WRs.
2) The Jags had a very physical training camp Buoye attributed to their success ( http://profootballtalk.nbcsports.com/2017/10/26/a-j-bouye-results-show-doug-marrone-was-right-to-put-us-through-a-tough-camp/).
This doesn't mean Marrone is more right than Koetter. They are only two data points, and maybe the Jags would've felt differently if Ramsey went on IR in training camp. But Buoye does say as hard as camp was, they noticed how much more physical and well conditioned they were when they scrimmaged against the Bucs. When you see a poor tackling, soft defense like the Bucs I do wonder.
3) Some posters have been saying one of the Bucs' problems is their large DEs. The Jags are having success with larger DEs. If anything, their size in their front 7 is fairly similar to the Bucs. The issue isn't size or lack of size. It's talent.