I have seen quite a few Tyrone Power pictures and I have to admit I have been disappointed many times. Not really with his acting per se, but more by the actual XXth Century Fox productions he was put in.
For example,
Nightmare Alley which I thought was going to be a tremendous film noir, turned out to be a real flop for me. Lack of atmosphere, weak script and very weak leading lady.
The same with
The Razor's Edge, I found the dialogue terrible (apparently, George Cukor refused the film after reading the script) and Tyrone is really struggling to build a reasonnable character. Somerset Maughan wrote a really good story but on the screen, it becomes a pensum. In both cases, Edmund Goulding shows his limits: the two film are slow moving and ponderous. But, I cannot underestimate the actions of Darryl Zanuck who probably meddled quite a bit in both films. After all, Goulding's productions at Warner's were really better shaped.
Then there are the Henry King films. I saw
Lloyds of London,
The Black Swan,
Prince of Foxes,
Captain from Castille,
King of the Khyber Rifles and
The Sun Also Rises. Of the lot, my favourite is
Captain from Castille; it's lyrical and beautifully shot on locations. The others lack the rythm and tension of the Flynn/Curtiz Warner productions. Henry King which made some tremedous silents and some great early talkies (
State Fair, 1933) seemed to have lost his way at XXth Century Fox under Zanuck. He probably lacked the artistic freedom he enjoyed earlier as director and producer of his films.
The Sun Also Rises is really typical of the literary adaptation supervised by Zanuck: just awful....
Another lovely swashbuckler is Mamoulian's
The Mark of Zorro
I think Tyrone was certainly a good actor, but, I very much doubt XXth Century Fox used him to the best of his habilities.