It's an odd year for complete games, that's for sure. We had three of them Sunday (5/17), but two of them were games in which pitchers went the distance in losses (both in the American League): the Blue Jays' Mark Buehrle in a 4-2 loss to the Astros, and Cleveland's Carlos Carrasco in a 5-1 loss to Texas.
What's odd here is the number of losing CGs occurring without analogous winning CGs happening at the same time, which used to be a relatively common occurrence as late as the 1980s.
Taking the lead in CGs in 2015 (with his second of the year) was Shelby Miller, who came within an out of the year's first no-hitter as he improved his record to 5-1 with a two-hit shutout over the Miami Marlins. It was Shelby's third consecutive "1S" game via the QMAX scale.
Overall, the 12 "officially recognized" complete games in 2015 have produced a 7-5 win-loss record for the pitchers who threw them. That's a good bit lower than what's usually the case in terms of CG WPCT, which is normally close to .800 these days.