[Editor's note: This is the site's first piece by new contributor Matt Goldman! Welcome him aboard.]

With the addition of Joe Maddon earlier this offseason and the Cubs' proclamation of contending for the NL Central crown in 2015, one thing was abundantly clear: It wasn’t going to be with Welington Castillo playing a major role. During the 2014 season, Castillo rated as one of the worst defensive catchers across MLB, and with the Cubs making real strides to upgrade their rotation, it was imperative for them to make a change behind the plate.

Ever since Castillo started catching games for the Cubs, his work behind the plate has been a disaster, culminating in a defensively atrocious 2014 campaign. Catching at the major league level is no easy task, but in Castillo’s case, the more experience he's gained, the worse he's become.

Welington Castillo 2012 2013 2014 Sample 3889 8300 7903 +Calls -40 -125 -183 RAA -5.4 -16.7 -24.3

Castillo’s zBall% (the percentage of pitches, caught within the strike zone, called a ball) was 16.8%, tying him for the worst rate among all catchers with a sample size over 7900; his oStr% of 6.0% (the percentage of pitches, caught outside the strike zone, called a strike) ranked dead last in MLB for catchers having as many opportunities as he had. Put simply, Castillo was great at making strikes look like balls, and inept at making balls look like strikes.

Theo Epstein and Jed Hoyer clearly believe in the importance of framing, and understood that a change had to be made. That change manifested itself in the form of Miguel Montero, after losing out on Russell Martin earlier this offseason. While he’s not a flashy name like Yadier Molina or Buster Posey, Montero has quietly been one of the best catchers in terms of framing pitches, and will provide an immediate boost to the Cubs in 2015.

Miguel Montero 2008 2009 2010 2011 2012 2013 2014 Sample 3321 7869 5763 9685 9749 8335 9535 +Calls 49 169 54 142 50 -17 180 RAA 6.5 22.5 7.1 18.8 6.6 -2.3 24

While Montero’s 2013 season wasn’t what we’ve come to expect from him, likely due to a nagging lower back injury, 2014 saw him rank 1st in oStr%, +Calls, RAA, and 4th in zBall%.

If we compare the differences in zBall% and oStr%, the disparity between Montero and Castillo becomes even more apparent. In 2014, Montero produced rates of 11% and 9.3%, respectively, translating to a reduction of 34.5% in zBall% and an increase of 55% in oStr% when compared to Castillo.

These zBall and oStr percentages are extremely important for any pitching staff, but particularly for the Cubs' hopes in 2015 and beyond, due to the tendencies of Jon Lester and Jake Arrieta. While some pitchers like Madison Bumgarner challenge hitters with good ol’ country hardball, both Lester and Arrieta love the fringe of the strike zone.

These heatmaps show just how much Lester and Arrieta rely on corner pitches. Thus, installing a great framer like Montero behind the plate will allow them to reap enormous benefits.

While defensive metrics are hugely important, it’s imperative to look at the offensive side of things to fully complete this analysis. Castillo clearly provides more power, but other than that, they are very similar hitters, with Montero having a slight edge in other categories.

Player (Year) AVG OBP SLG ISO BABIP wRC+ wOBA Miguel Montero (2014) .243 .329 .370 .127 .275 90 .307 Welington Castillo (2014) .237 .311 .389 .153 .288 91 .306 Miguel Montero (2015 Steamer) .250 .340 .379 .130 .299 100 .319 Welington Castillo (2015 Steamer) .242 .311 .389 .146 .294 95 .311

Montero owns a career BABIP of .306, so while his 2014 campaign was below what he normally produces, Steamer projects that number to rebound and return to normal levels in 2015. Overall, Steamer sees Montero as almost exactly average in terms of wRC+, wOBA, and BABIP for next season, and forecasts a 2.6 fWAR.

All the benefits Montero brings to the Cubs come at a cost of $40 million over 3 years. Initially, that may seem very expensive, but a closer look indicates that he's well worth the money. In 2014 alone, the difference in RAA between Montero and Castillo was an enormous 48.3. Using Fangraphs' ratio of 10 runs per win, swapping Montero for Castillo would have resulted in a difference of roughly 4.83 wins during the 2014 season. Even at the full difference between Montero's AAV of $13.33 million, and Castillo's 2014 salary of $530,000 (which will rise in 2015 due to arbitration), that translates to only $2.65 million per additional win — a number that any front office would love. Add that to the thrill the Cubs pitching staff should feel over Montero's arrival, and it becomes easy to understand why this trade makes perfect sense.

Showing their commitment to upgrading their pieces behind the plate, the Cubs announced the signing of David Ross this past Friday. He's another fantastic pitch framer, and someone the pitching staff can trust. In a sample size of only 3691, Ross was able to produce an RAA of 10.5, which was good for 13th in all of MLB. With this tandem of catchers, the Cubs have arguably the most elite combination of pitch framers heading into next season.

Montero's addition, along with the signing of Ross, sends a strong signal from the front office that the Cubs are all in for 2015. The good news for everyone involved is that along with Montero's defensive abilities, he already seems to be fully on board with the Cubs way.

I just been a Cubs for 24 hours and I love it lol — miguel montero (@miggymont26) December 10, 2014

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All statistics courtesy of FanGraphs, StatCorner and Baseball-Reference.

Matt Goldman is a Contributor for Beyond the Box Score. You can follow him on Twitter at @TheOriginalBull.