Here are the rules I went with:
Had to appear on the active roster for the Cubs according to Baseball Reference. So no Donaldson or Torres or any of the minor leaguers that have been traded away over the last few years.
I am going off of current statistical analysis of the 2019 season.
Player has to be on a current 25-man roster now (including those on the IL) or have at least appeared in games for a team this season.
Players were culled from the BR lists all the way back to the year 2000 - as their aren't many 19 year veterans out there these days.
1B - Tommy LaStella (Anthony Rizzo and Derrek Lee have pretty much held down this position for the last 2 decades. LaStella is about the only ex-Cub who has experience at the position currently on any active roster.)
2B - DJ LeMahieu (LeMahieu was one of those guys that wasn't really allowed to develop. Barney and DeRosa kind of squeezed him out and he has put together a pretty good classic slap hitter between the Rockies and now the Yankees)
3B - Jeimer Candelario (He never really has lived up to the promise that was once heaped upon him. He's been ok (not great) for the Tigers in their ever ongoing rebuild.)
SS - Starlin Castro (While he may no longer have the range to play at SS anymore, he's still an okay hitter and provides veteran leadership for the Marlins. Again, a guy I personally feel never lived up to all the hype around him.)
LF - Dexter Fowler (No longer the premiere CF he once was, Dex moved on and got paid. He's putting together a ho-hum season in St. Louis.)
RF - Jorge Soler (Soler rarely plays the field anymore as a defensive liability. However, he DH's primarily for a rebuilding Royals team. He's put in some long cold spells but has shown flashes of some of the praise that brought him up years ago.)
CF - Leonys Martin (He's still a light-hitting, base-stealing, defensive replacement with the Indians. He still strikes out too much to play everyday, but he's still fast enough to play CF. He's scrappy.)
C - Wellington Castillo (He's always been a defensive-first catcher. Despite what clubs, even the Cubs, tried to do to turn him into a starter. I don't believe he ever was one. He's struggled offensively, but still is a good pitch framer and catches alot of baserunners. He's entering the professional backup phase of his career at age 32.)
SP - Jake Arrieta (He was still good for 10 wins, 30 starts, and a sub-4 ERA last year with the Phils while the Cubs struggled to keep the 5th starter spot filled. I understand a gentleman wants a long-term contract and that's what sent him on but I would've liked to have seen what last year would've been like with one more year with Jake in the playoffs)
SP - Rich Hill (For Rich Hill, injuries have sidelined what could have been a Hall-of-Fame style career. His deadly curveball found its mark once he left Chicago and survived injury after injury. He's thrived in LA. Once again sidelined by injury, if he can keep his 39 year old body together, he's still a terribly effective mid-rotation starter.)
SP - Jeff Samardizija (Shark has always struggled with command and control. He's never been anything more than a longman reliever that fooled enough people into thinking he could be a starter. Shark was too much of a competitor to settle for it and has now turned himself into a starter over the last 12 years. He pieced together a few good years in Oakland, the White Sox, and now the Giants but he would've served himself better becoming a longman in Chicago's bullpen. He might've won a series ring that way.)
SP - Andrew Cashner (See Shark's info above. Cashner has similar problems with better stuff. He's 3 years removed from his best seasons in San Diego. Move him to a bullpen and let him turn that fastball up. A few of them might go yard, but the movement will be what sets them down in the 8th or the 9th at this point. For Baltimore, why settle for another 5+ ERA season from a guy you're overpaying?)
SP - Brett Anderson & Clayton Richard (You may only get about 100 innings out of Anderson because he can't stay off the IL but he'll win you a few ballgames with an ERA south of 4. Clayton Richard just eats innings like Cheerios and will do about the same thing for you for the games that Anderson doesn't start. Perfect 5th man in a rotation.)
RP - Hector Rondon (Rondon finally accepted a role as a high-leverage setup guy when he went to Houston. It made him salty for a time in Chicago because he felt he earned the closer job. Rondon is still doing well and is probably the best non-closer option out there that could certainly close. Blake Parker being the other.)
CL - Aroldis Chapman (As much as I don't like the guy, he's the lynchpin in the Yankees bullpen. He's a little less spooky to watch in the ninth than Wade Davis these days, who's been injured. I like Davis because he can go multiple innings but Chapman still has command at the 97 mph+ fastball when he dials it up.)