Contreras, 24, signed for $850,000 as a third baseman out of Venezuela in 2009. He moved behind the plate in 2012 and didn't reach full-season ball until the following year. The Cubs declined to protect Contreras on their 40-man roster following the 2013 and '14 seasons, yet he went unclaimed in the Rule 5 Draft both years.
A career .254/.320/.369 hitter entering 2015, Contreras broke out with a .333/.413/.478 performance at Double-A Tennessee, leading the Southern League in batting and extra-base hits (46) while claiming Cubs Minor League Player of the Year honors. He has been even better this season at Triple-A Iowa, batting .350/.439/.591 with nine homers (one more than his 2015 total) in 54 games.
Contreras has excellent hand-eye coordination and solid raw power that began to translate into production once he became more patient at the plate. He now walks nearly as much as he strikes out, and he projects as a potential .280 hitter with 15 or more homers per year.
Though Contreras' offense overshadows his defense, he can get the job done behind the plate. He combats the running game with a strong arm and has more athleticism and agility than most catchers. Contreras is still improving his receiving and game-calling skills, and working with Montero and Ross should help him in those areas.
Montero has missed time with a back injury and is having one of his worst offensive seasons ever, while Ross is a 39-year-old best suited for backup duty, so there's little doubt that Contreras would represent an offensive upgrade over either of them. At the same time, the veterans' defensive savvy has contributed to the Cubs' 2.66 team ERA, which easily leads the Majors.
Chicago already has a team that looks more than capable of ending a National League pennant drought that dates to 1945 and a World Series championship dry spell that extends to 1908. Contreras could enhance the Cubs' chances if he proves ready to handle a big league pitching staff.
Jim Callis is a reporter for MLB.com. Follow @jimcallisMLB on Twitter and listen to him on the weekly Pipeline Podcast. This story was not subject to the approval of Major League Baseball or its clubs.