On the back of the card is a list of other players from the team to wear that number and other MLB stars that also wore the number.
The set has 100 cards. With 30 MLB teams, there should be three or four players per team. The Cubs totally busted that, with seven players included. I'll go through the Cubs cards in numerical order.
#17 - Kris Bryant
Other Cubs Listed: Lon Warneke, Charlie Root, Guy Bush, Mark Grace
Player I most associate with the number: Mark Grace
Random thoughts: There was about a 50 year period between Root and Grace where #17 was worn by a bunch of mediocre players. I wonder if Bryant will be the last Cub to wear it?
# 22 - Jason Heyward
Other Cubs Listed: Dizzy Dean, Bill Buckner, Mark Prior, Paul Popovich
Player I most associate with the number: Bill Buckner
Random thoughts: Addison Russell wore this number last year but gave it to Heyward when he was signed over the winter. Class move by the rookie.
# 23 - Ryne Sandberg
Other Cubs Listed: Phil Cavarretta, Jim Tracey
Player I most associate with the number: Ryno and Carmen Fanzone
Random thoughts: It's a stretch to include Cavarretta on the list because he wore #44 from most of his career. And Jim Tracey?
# 26 - Billy Williams
Other Cubs Listed: Jimmy Fox, Moe Drabowsky
Player I most associate with the number: Billy Williams
Random thoughts: Topps included Billy - yea! Topps reused a picture for the upteenth time - Boo! A couple years after Billy was traded, the number was given to Larry Biittner. It was the oddest thing to see someone else wear it. I didn't like it at all.
# 34 - Jon Lester
Other Cubs Listed: Stan Hack, Frank Thomas, Cal Koonce, Steve Trout
Player I most associate with the number: Kerry Wood
Random thoughts: The Frank Thomas listed is the other Frank Thomas. And how could Kerry Wood be left off the list?
# 44 - Anthony Rizzo
Other Cubs Listed: Phil Cavarretta, Burt Hooton, Dick Ruthven, Kyle Farnsworth
Player I most associate with the number: Anthony Rizzo
Random thoughts: Cavarretta is listed correctly here. His number was unofficially retired, as no Cub wore it from when Cavarretta left in 1953 until Hooton used it in 1971.
# 49 - Jake Arrieta
Other Cubs Listed: Stan Hack, Kirby Higbe, Bill Hands, Jamie Moyer
Player I most associate with the number: Bill Hands
Random thoughts: Hack wore the number for just one season and shouldn't be on the list. Carlos Marmol used it for eight season and should be on the list.