CHICAGO -- Admit it. You were wondering what the Chicago Cubs got for three-time All-Star Starlin Castro. You were wondering when the trade happened, and you really started to wonder -- or even question it -- when Castro got off to a hot start with the New York Yankees.

Adam Warren may not be the known commodity that Castro is, but he’s off to his own hot start. Middle relievers don’t get much fanfare, but let’s start with the fact that Warren is the only non-starter to win a game for the Cubs. In fact, he has won two, including Tuesday’s 4-3 nail-biter over the Milwaukee Brewers.

“He’s gotten better from spring training until now,” manager Joe Maddon said after the win. “He’s very assertive. Pitches that can go both ways to righties and lefties. A guy like that can pitch to both sides, to both hitters, to lefties and righties successfully.”

In seven appearances this season, Adam Warren hasn't allowed a run. Dylan Buell/Getty Images

Warren threw two scoreless innings Tuesday, striking out three. That was his entire line in the box score. While Addison Russell was the hitting hero and Javier Baez was the one on the base paths -- a sliding hero, if you will -- every win needs a guy on the mound. After Kyle Hendricks left in the fifth inning, Maddon made a point of allowing Warren to pitch two crucial innings in a 1-1 game. He could end up doing more, maybe even a spot start.

“Part of what I did tonight was to get him stretched out in case there was a need for that,” Maddon said. “He’s in the lead based on being more stretched out right now.”

Warren passed Trevor Cahill as that guy, should there be a need for a starter outside the regular five. He has also quickly become the key guy in a tight game, as evidenced by his Tuesday outing. And if wins don’t do it for you statistically, Warren hasn’t given up a run in seven games as a Cub.

“A lot of my game is keeping the hitter guessing,” Warren said. “I’m not going to blow you away with a certain pitch or certain stuff. It’s a mix of everything.”

That mix has resulted in just two hits off him in eight innings.

“He has a really good cutter that he can throw in fastball counts to keep guys off balance,” catcher David Ross said. “He can [throw] back door to lefties to get a free strike. He really knows how to pitch.” Ross also said Warren has “94 [mph] in his back pocket if he needs it.”

There’s a lot going on in Warren's arm and head, and the results show it. He’s also among the quiet guys on the team.

“Him and Addy [Russell] hang out because neither one of them talk,” Ross joked.

Both spoke loudly on the field Tuesday, helping the Cubs to their 15th win. Asked if he was excited to pitch two innings, Warren justified Ross’ description of him as low key.

“It was interesting sitting down and getting back up,” Warren responded.