Have the Cubs finally created a sustainable Starlin Castro?

On August 6th, Starlin Castro lost his starting job. He was one of the worst players in baseball for the first five months of the season, and Joe Maddon relegated him to the bench. At one point during the trade deadline, it looked like the Cubs were getting ready to send him away, but it now seems obvious that their best "move" was to hold onto him. It's been an incredibly up and down season for the former shortstop, but thanks to some mechanical adjustments, Castro has been able to transform himself into a power hitting second baseman.

While a hitter can point to adjustments in his swing at the plate, it's often difficult to see the specific change. It can be something as minor as how they grip the bat, or how they load their hands before the pitch is delivered; but with Castro, it's impossible not to notice the difference.

Castro eliminated his open stance, and he's now more upright. He also altered his leg kick, which can be seen here, and here. The changes have led to a remarkable turnaround, as Castro has been one of the league's best hitters since becoming an everyday player again.

These numbers are undoubtedly guilty of two things; a small sample size, and arbitrary end points. However that doesn't inherently mean that the results aren't significant, and that we should ignore them. While it would be nice if Castro could reduce his strikeouts and increase his walks, it's interesting that his rates haven't changed, and is rather telling of what Maddon and his hitting coaches have done.

Trying to make swing adjustments during the season is hard enough, so rather than attempting to overhaul Castro's entire approach, they only made mechanical changes. While his recent BABIP is unsustainable, his zone profile suggests that Castro's new found success could be more than just a hot streak.

For the past season and a half, nearly all of Castro's ISO was generated on pitches out of the strike zone, but that's no longer the case. Now he's hitting pitches within the strike zone, and he's also added more than seven feet to his average fly ball, line drive, and home run. From 2013 through August of this year, Castro averaged a batted ball distance of 263.8 feet, but since taking over second base, it's risen to 271.1 feet.

Over his career, Castro has largely been a below average hitter. He's had success before, but he's never been able to carry it over for more than one season. In 2014, he posted an ISO of .146, a wOBA of .341, and a wRC+ of 117. It seemed like Castro had finally figured it out, but he unfortunately couldn't keep it together, and was well on his way to having the worst season of his major league career.

However thanks to his new stance, not only has his season been salvaged, but he's resurrected his career for the moment. Regardless of how this season ends for the Cubs, they should be ecstatic about the possibility of productive Castro. He's signed though 2020, and if he can have sustainable success, rather than just for stretches at a time, Chicago could have a cost controlled infield for years to come. Anthony Rizzo is under contract through at least 2019, and Kris Bryant and Addison Russell are finishing up their rookie years. The Cubs revolution is here, and the latest to join the fun is Castro.

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Matt Goldman is a Featured Writer with Beyond the Box Score and a Contributing Editor at MLB Daily Dish. You can follow him on Twitter at @TheOriginalBull.