My own bias is that PTs that are either former (or active) dancers in addition to PTs, as well as PT clinics with lots of them, tend to be much better than average. The reason I mention that is that in the NY/NJ area there are a number of these. Same true for PTs who are powerlifters, etc.
Back pain is funny in that you can have two people, both with disks that look the same, and one has excruciating pain and the other no symptoms. One reason more doctors are getting hesitant to operate is this fact, combined with the fact that surgery doesn't seem to offer better results than PT.
There's a lot of little stuff, like being able to touch your toes, or not, and various measures of "core" strength, that correlates strongly to whether someone has back pain, or not. A good PT will likely test your ability to do a lot of this stuff.
I'd read up on the epidural cortisone stuff more. The thing about them is that they don't by themselves necessarily help your long-term outcome, though they can make your near-term existence much better when they work. So the other rehab is still key. If you and your doc conclude that one's warranted and you trust your doc (otherwise get another doc now) they're not always super-painful.
edit: I had severe inflammation in the lower back from a fall a while back and recovered fine. That's different from your injury, so while I did benefit from an epidural myself you shouldn't take anything from that. For a couple weeks it was very hard to get into or out of bed, etc. 6 months later I was fine and actually felt that because of the good input during PT I came away better athletically.