Chicago Cubs: When do you start worrying about Jon Lester’s struggles?

After a superb first-half showing, Chicago Cubs left-hander Jon Lester has fallen flat since the All-Star Break. When do we start to legitimately worry?

Right up till the Midsummer Classic, Jon Lester pitched like a true ace. He led the Chicago Cubs to the league’s best record, earning his fifth career All-Star selection. In mid-July, he looked likely to crack 20 wins for the first time in his big league career.

But, suddenly, things took a turn for the worse. After cruising through his first 19 outings to the tune of a 2.58 earned run average, something changed. In his four second half starts, the three-time World Series champion carries a bloated 8.53 ERA to go along with a 1.895 WHIP.

His strikeout rate is down and walk rate is up. After serving up 13 home runs in 111 innings and change, he’s already allowed six in just 19 frames since the break. Given the up-and-down efforts put forth by the rest of the staff, an erratic and ineffective Jon Lester is a major concern for this team as they chase a third-straight division title.