Walsh even recommended Bolin to the James Gang because he thought he was so good. Fox, Peters and Kenner had no idea who he was and then first listened to Cobham's Spectrum (at least that is what Fox has said, but they must have listened to Spectrum pre-release then, that album only came out in Oct 73, by which time they had already released Bang with Tommy) initially wary how a "jazzer" like Tommy was to fit in with them.
(People always think that the wild intro solo is Tommy - it's not. It's Jan Hammer on synth. Tommy
doesn't make a solo playing entrance until 01:50, he's mixed to the right, Jan to the left. No less
impressive though.)
But then after the first audition - much like with Purple a few years later - they were rapturous. He brought along tons of ideas, a gentle soul and looked wild.
Spectrum impressed a lot of people back then, among them Jeff Beck (who then while still with BBA discovered Jazz Rock and entered his Blow By Blow/Wired phase in inspiration) and even Deep Purple who invited Tommy to audition on the strength of that album. A record that just spoke with people at the time, it's very much a "live in the studio" affair wth almost no doctoring. At 01:46 you can even hear Tommy break his high E-string after another bending excess, yet he continued to solo and they left the track as is, wishing to keep the inspiration captured.
I don't know if Tommy was ever a "better" guitarist than Joe Walsh (who has strengths of his own), but he was certainly good enough to not bore Jeff Beck. And for Jeff to play bass for him. (The Tommy Bolin Band was opening for the Jeff Beck Group at the time.)