By Chris Emma–

(CBS) Boos rained down upon Cubs left-hander Jon Lester as he slowly strode from the mound to the dugout two outs into the first inning at Wrigley Field on Sunday.

Lester’s line was just two-thirds of an inning, with 10 runs allowed (four earned) on six hits, which included a grand slam and solo home run back-to-back that were followed by a chorus of boos. The Cubs dug themselves a 10-0 hole before they took an at-bat and lost in ugly fashion to the Pirates, 14-3. One could only hope that was rock bottom.

The defending World Series champions stumbled to the All-Star break at 43-45 but not before discussing the boo birds. Lester said he was embarrassed, while manager Joe Maddon didn’t fault the fans for their response. Kris Bryant said he should’ve been booed for his costly error that help create the onslaught that followed.

There were enough boos to go around for everybody on this Cubs team entirely underperforming to its potential. The “Try not to suck” slogan was a lot more fun a year ago.

During their first half filled with inconsistencies, the Cubs have tried team meetings and experienced some triumphant wins, but none have turned their tide of mediocrity. It’s a group full of players falling well short of the projections. Sure, these Cubs are still young and struggles like these aren’t unprecedented, but all of this would’ve sounded preposterous in 2016 as the Cubs rolled through the rest of baseball to the tune of 103 wins and a World Series title.

Kyle Schwarber is hitting .178, Addison Russell has regressed and the starting pitching that carried the Cubs a year ago has a 4.66 ERA. The list of concerns runs long.

The Cubs could very well be fine, and this may just be a first-half fluke. The metrics beg to differ. The Cubs are 13th in cumulative WAR and 18th in wRC+ (weighted runs created plus). The pitching staff that topped the league last season is 12th with a 4.25 FIP (fielding independent pitching) and the rotation is 15th with a 4.50 mark. Even the team defense — historically elite a year ago — has been below average, ranking 14th in UZR (ultimate zone rating).

President of baseball operations Theo Epstein has emphasized that the answers are in the Cubs’ clubhouse, but he can’t stand pat on this team and assume its many flaws will revert to what’s expected. At the break, the Cubs are 5.5 games back of the NL-Central leading Brewers. Epstein can still prioritize 2017. Consider what Epstein said last July after a win-now trade of top prospect Gleyber Torres for closer Aroldis Chapman.

“If not now,” he said, “when?”

Such a mindset should still remain as the Cubs’ baseball brass balances its hopes with concerns. Epstein has been open about his faith in the individuals on this team. Now, he must put action to those words and do what it takes to better the Cubs’ chances.

Prized prospect Eloy Jimenez, the 20-year-old outfielder who has light-tower power, should be considered a trade piece to acquire top-end pitching at a team control. Like Torres, parting with him would be a steep cost but one well worth improving the Cubs’ opportunities ahead. They need starting pitching desperately — both for 2017 and beyond. It’s likely only Lester, Kyle Hendricks and Mike Montgomery return to the rotation next season.

Athletics right-hander Sonny Gray and Rays right-hander Chris Archer should top that list. Tigers right-hander Justin Verlander makes sense if absorbing his cost ($78 million after this season and with vested options) means paying less in prospects. Calls on White Sox left-hander Jose Quintana won’t go far, as they’re looking for another heist, and they may well get it.

Conversations should start with Jimenez, a talented outfielder who would emerge at a position filled beyond capacity for the Cubs. If acquiring pitching means parting ways with Albert Almora Jr. or Ian Happ, the Cubs should consider. Even Schwarber shouldn’t be viewed as untouchable in trade talks anymore.

These are hard realities to reconcile, but so is 43-45 for a team that just won the World Series. This isn’t just a championship hangover — the Cubs are what their record says. It could all turn for better in the second half. A major winning streak would be considered no surprise. The NL Central is within reach and the Brewers aren’t frightening by any means.

But this team has earned its boos through a major letdown this season. Fans expect much better from the Cubs, because they’ve set a high standard.

Epstein must move forward by addressing the Cubs’ flaws to keep the championship window as open as possible. So, if not now, when?

Chris Emma covers the Bears, Chicago’s sports scene and more for Follow him on Twitter @CEmma670 and like his Facebook page.

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