One of the main objectives of any sports' general manager is to take an objective view of his team's performance, then spend the off-season to upgrade positions lost or of need.
Objectively, 2017 Cubs fell down the sink hole with inconsistent hitting, poorer defense than 2016 and worn out pitching down the stretch.
The team lost two starting pitchers, a closer, bullpen arms and back up catcher.
The team has major needs in the pitching department (2 starters, a closer and relievers).
The team also needs to find consistent .300 hitters to balance out the feast-or-famine hitters. A traditional lead off hitter would be nice, too.
As it currently stands, Tyler Chatwood was signed to be a starting pitcher. He projects to be a back of the rotation arm. So does he replace Arrieta in the rotation? No. Does he replace Lackey? Maybe. But the other starter on the depth chart is AAA Eddie Butler. He does not appear to replace or upgrade either Arrieta or Lackey.
The Cubs signed reliever Brandon Morrow. He is projected to be either the set up man or closer. Is he an upgrade over Wade Davis? Probably not. Morrow was the workhorse for the Dodgers in the playoffs, throwing in 14 of 15 games. As we have seen in the recent past, managers who abuse pitchers at the end of their contracts usually have a bad next season (example, Chapman).
Drew Smyly was signed to a two year deal, but he had Tommy John surgery last July so he may not even pitch in 2018. (The current Cubs philosophy of signing injured pitchers and pay for a year of rehab without production is very odd.) You really cannot count on Smyly being a starter or reliever.
The Cubs acquired reliever Dario Alvarez. Is he an upgrade from Hector Rondon? No. Alvarez has only 56 major league appearances.
As we stand today, none of the Cubs off-season moves have objectively upgraded the roster.
What still bothers many is that the Cubs could have made a major upgrade by trading for Giancarlo Stanton. Objectively, Stanton would have been the best outfielder on the Cubs roster. He would have only cost one 25 man roster player (Baez or Russell) and two minor leaguers.
Unless the front office believes that they have internal solutions to their roster problems. But just counting on a player to have a "rebound" year is more hope and an position upgrade.
A Stanton trade would have opened up second base to be platooned by Happ and Zobrist. Heyward would have been moved to center with a platoon with Almora. Schwarber and Happ could platoon in left field. And Stanton would have anchored the line up at clean up spot, protecting Rizzo.
It is still early on a slow hot stove winter, but clearly the Cubs still need to upgrade several positions.