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Koppen should be prepared for a full season of duty. The Broncos still are holding out hope that Walton will return by November, but that is believed to be a best-case scenario at this time. It's possible Walton won't play a down in 2013.
Koppen, 34, isn't a dominant player by any stretch (he graded out 22nd among centers last season, according to Pro Football Focus), but the Broncos are fortunate he was on the market as a fallback option.