Four years ago this month, J.D. Martinez was dropped from the Astros' 40-man roster and subsequently went unclaimed by the 29 other Major League teams. In the final week of the next spring, Houston released him from its Minor League camp.
Tigers coach Dave Clark, who had been with the Astros and knew Martinez well, convinced Detroit to sign Martinez to a Minor League contract, and 17 games, 10 home runs and 22 RBIs with Triple-A Toledo later, Martinez was called back to the big leagues by the Tigers.
Flash forward to this November. Martinez is one of the most coveted free agents on the market. Surprised? Don't be.
Is Martinez the perfect player? Not really. His defense is questionable.
Martinez is, however, dang good at what he does -- hitting. In the four years since being released, he has hit a combined .300 with 128 home runs, 124 doubles, 10 triples and 350 RBIs. And in Martinez's 2 1/2 months in helping the D-backs claim a National League Wild Card berth, he belted 29 home runs in 232 at-bats, providing big-time lineup protection for Paul Goldschmidt.

And Martinez has earned it. His offensive emergence hasn't been by chance.
In the midst of his struggles with the Astros in 2013, which included missing 44 games due to injury, Martinez went to work. He studied videos of hitters he admired, including Houston teammate Jason Castro, and the reality set in -- Castro's swing path allowed him to keep his bat in the hitting zone longer than Martinez.
"I walked out of the video room," Martinez said in the summer of 2014, "and I saw a clip on television of Ryan Braun, and he had that path. I went back in the video room. I had the videos [of Castro and Braun] side by side. They were very similar.
"We were playing St. Louis and I look at Allen Craig, Matthew Holliday. They had different approaches, but they got to the same place. They had their bats in the zone so long. Mine was not remotely close to them."
It is now, because Martinez worked to get that way. He even returned to winter ball, playing in 23 games with Leones de Caracas in Venezuela in 2013-14, hitting .315 with six home runs in 24 games.

Martinez's excitement about getting to spring training died quickly. The Astros didn't feel he was a fit in light of the young players they had coming. He was released.
Martinez was disappointed, but not for long.
"They did me a favor," he admitted. "If they didn't like me, I was better off being released than going to the Minor Leagues and being buried. I was better going off somewhere I could get a chance."
And to Martinez's credit, he has taken advantage of that chance. Now, as a prized free agent, he waits to reap the benefits of his perseverance.