Ryan’s medical update on Sanchez seemed to carry an underlying message. Sanchez has proved to be a much better quarterback this season than he was as a rookie, when Ryan made a point of not relying on Sanchez to win games on his own, especially in the playoffs.
Now that Sanchez has proven he is more capable of playing his position."The traditional past participle is proved, which is much more common than proven in the UK even today. But in both British and American English, proven has been gaining ground, especially since the 1970s, and in the American section of the Google books corpus has all but pulled abreast of proved.
Frequency of past participles of prove in British section of Google Books corpus.
Frequency of past participles of prove in American section of Google Books corpus.
BTW, any theories about those humps around the ends of the two world wars?