How success as a reliever made Cubs’ Keegan Thompson a better starter

Cubs right-hander Keegan Thompson started against the Cardinals on Thursday, opening a five-game series at Wrigley Field.When Cubs right-hander Keegan Thompson looks back on his development over the past year, he’s most proud of the way he moved past his struggles at the end of last season.

“Being able to go through success and then failure, and come out the other side I think is a big thing for me,” he said in a conversation with the Sun-Times. “Because you’re not going to have success every single time [you go out].”

Now, after a dominant start to the season, Thompson is back in the rotation, at least for the time being. On Thursday he allowed three runs in 5 \u2153 innings in a 7-5 win…