There's no trade that's going to fix what's wrong with the Cubs.
The players with the 2016 World Series rings got the '17 team into its current hole, and they'll have to be the ones to climb out of it. Theo Epstein will look for ways that he can add useful reinforcements, but the current issues are far more widespread than a year ago, when the Cubs needed only bullpen help.
Oddly, the bullpen is probably the area that needs the least attention at the moment, with Wade Davis turning in an All-Star season after taking the closer's baton from Albertin Chapman in the offseason.
To reach 90 wins, the Cubs need to go 47-27 in the second half, and to get there requires a serious about-face. Here are five areas that need to be addressed, and the most likely candidate to fill the need.
1. Front of the rotation: Jacob Arrieta
You could say the Cubs had three No. 1 starters a year ago, but the pitcher they really need is the Arrieta from 2015, when he turned in a historic second half en route to winning the National League Cy Young Award. Diminished velocity and fastball command does not suggest we'll see that pitcher again. But how about this?

What if Arrieta could cut his ERA by 1.91 from the first half to the second, as he did two years ago? That would mean a 2.44 second-half ERA this time around (after a first half in which he was 8-7 with a 4.35 ERA), making Arrieta a very strong complement to Jonathan Lester, who was pitching well before allowing 16 runs in 5 2/3 innings in his last two starts.
2. Rotation depth: Kyle Hendricks
Nothing's been more costly for the Cubs than the regression of a rotation that operated like a well-oiled assembly line last season, turning out a Majors-best 81-39 record with a 2.96 ERA. The issues with Arrieta and Lester have contributed to a 4.66 ERA this season, which ranks eighth in the NL.
Hendricks, who last year became the first Cubs pitcher since 1945 to lead the league in ERA, could provide a big lift when he comes off the disabled list. He's been sidelined since June 4 with an injury to his middle finger, which has made it tough to grip the ball.
Hendricks made a rehab start Monday, and he shouldn't be out much longer. But the righty can't fix anything by himself, as John Lackey is on the DL with plantar fasciitis is his right foot and the three replacements for fifth starter Jason Hammel have gone 7-8 with a 5.23 ERA.
Epstein will add a starting pitcher if he can find a controllable one at a price he can swallow. Don't look for him to expend prospect capital on a rental starter.
3. Leadoff hitter: Jonathan Jay
William Fowler has been badly missed.
The Cubs have looked at almost every leadoff option imaginable after Kyle Schwarber struggled in the role, and results haven't been good. They're eighth in the NL with a .322 leadoff on-base percentage and 11th with 52 runs scored from that spot.

While Jay was signed to mentor Albert Almora Jr. and add outfield depth, he could take over center and be an everyday leadoff man. Jay hits left-handed but has a better OBP against lefties (.405) than right-handers (.378). He hasn't been as reliable in the leadoff spot as down in the order, however.
Another problem with this plan is Ian Happ is contributing as a rookie and has gotten more playing time in center than anywhere else. So maybe Happ and Jay share center, even if that leaves nowhere for Almora to play.
4. Middle-of-the-order bat: Schwarber
The Cubs had three hitters with 95-plus RBIs last season, but they could wind up with Anthony Rizzo as the only hitter to reach that mark in 2017. Kristopher Bryant, a victim of the leadoff woes, is on pace for 33 home runs but only 70 RBIs. Addison Russell is hitting .230 with seven homers and 29 RBIs.
Schwarber paid the price for his .178 average with a remedial trip to Triple-A Iowa. A big second half from him would fix a lot of what has ailed the Cubs. He looked more comfortable at the plate last week, going 4-for-10 with a home run and two doubles in the past three games. He carries a ton of responsibility for a 24-year-old in his first full season.
5. Defensive certainty: Russell
Last year's Cubs were the best defensive team in the Majors since the early 1980s. This year's team started poorly in the field -- in part because of Fowler's departure and Schwarber's return as a left field regular -- but has rebounded to rank sixth in MLB.com's Defensive Efficiency metric.
Credit Javier Baez, Jason Heyward and Rizzo. Russell has played well, but his issues at the plate and off the field contributed to him starting only 65 games at shortstop. He's still piled up 13 Defensive Runs Saved per FanGraphs, matching the Angels' Andrelton Simmons for most at the position, but the Cubs need him out there more often in the second half. They work best with him at short and Baez at second base (although, yes, Baez can play spectacular defense at short himself).