Andy Reid didn’t exactly peel back a layer of the mystery surrounding the Chiefs’ lineup and rotation for Sunday’s game at the Denver Broncos. Actually, when announcing earlier in the week that rookie quarterback Patrick Mahomes would get his first NFL start, Reid may have revealed more than he intended. At least based on his experience in a similar situation. Five years ago, the Chiefs headed to San Diego locked into their playoff spot, as is the case this year. In 2013, Reid suggested general lineup changes could occur but specified none — not even the career first start for backup quarterback Chase Daniel. “I thought I did,” Reid said, when asked why he publicly announced Mahomes as a starter at midweek this time. Reid’s memory of that game’s benefit, which included turning-point moments in the careers of a pair of Chiefs players, is clearer. “I thought it was a positive, and I’ll try to give guys an opportunity this time too,” Reid said. “I have a lot of confidence in our younger guys. I think it pays off for you down the road.” It did for current safety Ron Parker and defensive end Allen Bailey.