As you probably already know, the San Diego Chargers have won 19 out of 34 games under head coach Mike McCoy. That's a pair of 9-7 regular seasons and a 1-1 record in the playoffs. It's good for a win percentage of .559 or 8.9 wins over a 16-game season. That mark is neither impressive nor particularly objectionable. It also suggests neither improvement nor decline as the Chargers' strength of schedule differed by only .016 from 2013 to 2014.
It helps to start with head-to-head matchups against the division to get a real idea of how successful McCoy's Chargers have been. The Denver Broncos are inarguably the Chargers' chief rival for the divisional crown each year. Unfortunately, they are a horrendous 1-4 against the Peyton Manning-led Broncos. That alone basically knocks the Chargers out of contention for the AFC West title each season.
The next biggest rivalry is with the Kansas City Chiefs for the Wild Card spots. In 2013, both made the playoffs and in 2014 neither did. The Chargers have split 2 games a piece with the Chiefs. One of those Chargers wins was against Chiefs' second-stringers while KC was resting up for the playoffs and that required a missed field goal by Ryan Succop and overtime.
The Chargers have mostly taken care of business with regard to the division's basement dweller only dropping one out of four contests.
Overall though, 6-7 in the division isn't really getting it done in that regard. As for the conference as a whole, a mark of 13-13 is only slightly better, and not likely to result in too many playoff appearances without a whole slew of things outside the team's control breaking in their favor (as we saw in 2013).
19-15 isn't a horrible record, but a losing record in the division and going .500 in conference is a recipe for mediocrity at best. Hopefully 2015 is the year that McCoy and the Chargers get back over .500 in division and conference.
Setting aside divisions and conferences, what about good teams and bad? In two seasons, McCoy's Chargers are 9-9 against teams with winning records, 2-2 against .500 teams, and 8-4 against teams with losing records. Fattening up on the weak part of one's schedule is important, but if San Diego is going to push into that next tier of legitimate championship contenders they're going to need to do better than break even against teams that are .500 and better.