Martin Perez, the 23-year-old left-handed sensation in the Rangers' starting rotation, takes the mound Tuesday night in Arlington in the midst of a 26-inning scoreless streak.

Perez will toe the rubber one night after Yu Darvish was roughed up a bit by the A's, surrendering four earned runs in 3.1 innings, his shortest outing as a Ranger.

Through five starts, Perez is 4-0 with a 1.42 ERA and a WHIP (walks + hits per inning pitched) of just 0.92. He has thrown back-to-back three-hit shutouts.

Perez has compiled an American League-leading 1.89 WAR through his five starts, which is tops among pitchers in Major League Baseball. That is almost a full game higher than Yu's mark of 1.09.

Darvish is 1-1 with a 2.59 ERA and a 1.24 WHIP thus far in 2014.

Perez has also been more efficient in his five starts this season. He's thrown just 13 more pitches than Darvish, but has pitched 6.2 more innings.

Now, the pedigree of Darvish his impressive career rate of 11.1 strikeouts per nine innings and Cy Young runner-up finish last season gives him the edge in the 'ace' conversation. But is it time to entertain the idea of a changing of the guards at the top of the rotation?

Perez has a career 2.73 ERA against current division opponents, compared to Darvish's 3.82. Perez's sample size is much smaller (98.2 innings compared to 216.2 for Yu), but effectiveness against division rivals the opponents a team plays the most is something an ace pitcher must have.

Some of Darvish's biggest struggles (which are few and far between in a stellar start to his career) have come against division foes. Namely, the Athletics and Mariners.

Don't get me wrong: Yu has been outstanding in his Rangers career, and one start doesn't make it a bad season in 2014. But his dominance waivers against division opponents.

Perez's success against AL West teams could easily change over his next 117 or so innings, roughly the margin that separates his intra-division workload from Darvish's. But thus far, he's been phenomenal against them.

He's been phenomenal all year. And he gets a chance to keep both of those trends going against Oakland Tuesday night.

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