Cubs have the best corner infielders in MLB bar none ("D" + OBP + power), Russell is a top notch plus fielding and hitting SS. The other starters are OK, like .220 hitting RF Heyward is a great defensive outfielder. Zobrist is a solid hitter. Fowler is a streaky hitter.
Right now Lester is one of the top 3 starters in MLB, especially for a money game, but Arrieta has lost his mojo, and Hendricks had a fluke year but it is highly unlikely he will continue this way. Chapman is a great closer. The rest of the staff is so-so.
Cubs were very fortunate this year, suffered very few injuries compared to others (chubby slugging LF Schwarber for the year, Fowler a couple times for a few weeks).
Sure they could win it all but after they beat SF in 4 or 5, LA or Nats could knock them off easily and if they make it the AL winner would be equal to the task.
(Arrieta is having problems, another good idea tonight is SF TT over 3, though they are not hitting, and the weather might be chilly and home run adverse... so SF and SF "O" 3 runs).