This is a topic close to everyone who ever wanted to read tomorrow's newspaper today.  The authors went beyond speculation and theory and actually conducted their own original research into whether manager consistency can serve as predictor of performance.  Make your own guess and then see what the authors found.

Pursuing Performance Persistence: Consistency, Information Ratios, and Style
Thomas H. Goodwin, Ph.D., Frank Russell Company and
Leola B. Ross, Ph.D., Frank Russell Company