But a number of people close to Contreras believe his game picked up on the mound when his wife and two daughters were allowed to defect from Cuba and join him in the United States at the end of June in 2004. From July 2004 through the present, the right-hander holds a 32-13 record.
As Contreras explains it, through translator Ozzie Guillen Jr., going from being completely alone to having your family right by your side only can improve your overall outlook on life.
"It's a huge difference," Contreras said. "[Prior to a recent start], I was talking to my wife and we had lunch as a family, everyone together. Before, I made one bad pitch and it would stay with me all day and all night.
"I would go home and be by myself. I take my work to my house by myself. Now, I get home after a game, play with my daughters, talk to my wife and keep my work at the stadium and it makes a big difference."
The arrival of Contreras' wife, Miriam, and his daughters, Naylan and Naylenis, has been pointed out in regard to the right-hander's development by everyone from White Sox pitching coach Don Cooper to Hall of Fame-bound hurler Roger Clemens, Contreras' teammate with the Yankees in 2003. Contreras has presented glowing reviews of Clemens as both a friend and a mentor, and Clemens returns the compliments to Contreras as a person and a member of the same starting rotation.
During Houston's 2006 Interleague trip to U.S. Cellular Field, Clemens talked about how much fun Contreras was to work with and the intense work ethic he brought to the rotation. Clemens described Contreras as a "big-body guy" and pointed out how he loved the strength in Contreras' legs.
Clemens even went as far as to disseminate between the two hurlers' out-pitches, which are both a variation of the split-finger. Contreras' splitter acts more like a forkball, by virtue of him hooking a seam when he throws it.
When Clemens ultimately was called upon to explain Contreras' rise to such an elite pitching level, the 342-game winner turned to Contreras' happy family affair.
"I thought his career took off greatly when he was able to get his family here with him," said Clemens of Contreras. "I saw a tremendous easing of his mind. I think anyone could understand that.
"Pitching is not even secondary. It's way on down the list when you talk about that. He got comfortable in New York and then once he had that turnaround with his family, everything has really taken off."
Contreras was traded from the Yankees to the White Sox, in exchange for Esteban Loaiza, shortly after his family defected. As Cooper pointed out, Contreras' final two months of 2004 with the White Sox, filled with wildness and high pitch counts, didn't exactly endear him to the South Side faithful.
But bringing in Orlando "El Duque" Hernandez in 2005, a fellow Cuban defector who understood what Contreras was dealing with on a daily basis, helped Contreras match his baseball life to his personal life. Contreras also took advice from Hernandez and started dropping down from different arm angles, giving him better control, and making him virtually unbeatable.
It was just one month ago when Guillen talked about Contreras as a possible American League starter for the All-Star Game. As of Monday, Contreras will be part of Tuesday's contest but will not be part of the active roster after throwing 114 pitches Sunday. It's an issue that doesn't remotely bother Contreras.
"No, I'm not upset," said Contreras through a translator on Monday, "Yesterday was a long game and I threw a lot of pitches. I just have to get ready for Friday. I'm not bothered by it at all."
Guillen explained that Contreras has an extensive pregame warmup ritual, almost bordering on quirky, and he didn't want to risk Contreras not being able to go through his normal routine after Sunday's draining performance. Just one member of the White Sox family looking out for another.
Dampening Contreras' spirits is a very hard thing to do, at this point. His wife is expecting their third child, and their first son, and Contreras has a World Series title, a three-year, $29 million deal with a team he loves and an All-Star appearance under his belt. His focus is on Friday's start at Yankee Stadium, and of course, enjoying these few days in Pittsburgh with his wife and daughters.
"Regardless of what job or occupation you have, put yourself in his shoes for a moment," said Cooper of Contreras. "I know when my family ain't with me on the road, my life ain't quite the same.
"Compound that with miles and miles of separation. Compound that with not knowing about their safety. Combine that with maybe being alone. There are so many things that can be brought about you when your family is not with you.
"When you are happy and everything is right in your life, you can do a better job at whatever job you have," Cooper added. "I don't care if you are a pitcher for the White Sox or if you are sweeping streets."