The leagues that take place after the MLB regular season are referred to as the Winter Leagues even if they don't play in the winter. The Arizona Fall League (AFL) will be over before winter rolls around, but it's included in the winter leagues because it's just easier.
The Cubs have 7 players who have played so far in the AFL, 8 in the Dominican Winter League (DWL), 4 in the Mexican League (LMP) and 9 in the Venezuelan Winter League (VWL). There are likely more on some of the Caribbean leagues, which includes the DWL, VWL and LMP. At the bottom of this post are the stats so far for all the players, including OPS+ for batters and ERA+ for pitchers. This wasn't particularly easy to calculate.
There aren't any available park factors for these leagues. At least not any trustworthy ones so it isn't adjusted for ballpark. Because the team batting pages didn't include SH, which is necessary to calculating OBP, I took a weighted average of the team's AVG/OBP/SLG. I checked this by calculating the average and SLG and it's quite close to the numbers are good enough, but not exact.
Keep in mind the sample sizes. I'll update these each week (stats are through Sunday).