During the last four years, it has become customary to look at the rankings for American League teams in starting pitcher ERA and find Minnesota at the bottom. In 2011 they ranked 12th. In 2012, 2013 and 2014, they ranked dead last, each time finishing with a mark above 5.00.

When you look at the current ranks, you find the Twins' starters not last, and not even in the bottom five, but ninth out of 15 AL clubs with a 4.37 ERA. That's still not great, but it represents something we have been waiting a long time to see: progress.

The odd thing about the relative success of the Twins' rotation is that it hasn't been backed up by indicators that they're actually pitching all that well. Minnesota starters rank last in the AL in strikeouts, second-to-last in opponents' batting average, and 11th in ground ball rate.

In other words, they're not really excelling at anything.

This could lead one to reason that the starting corps is due for some major regression, and bound to return to its familiar standing among the league's worst. That is possible.

What I see, however, are signs of promise. Here are three reasons why I believe the Twins can hang around the middle of the pack in terms of starting pitcher ERA, which would be an enormous victory considering their recent history.

Some wacky trends are bound to normalize.

Over at 1500 ESPN, Derek Wetmore wrote a great column this week about why Kyle Gibson's early-season success won't sustain if he keeps pitching the way he has. That's absolutely true; walking more batters than you strike out is a recipe for disaster, and one that will catch up with Gibson soon if things don't change.

But things almost have to change, and we might have seen the start of it on Tuesday night when he fanned five of the last six Tigers he faced in a seven-inning gem. Gibson had entered that start with a 2.7 K/9 rate, and there is nothing in his history to suggest that was going to endure. Last year the lowest qualifying rate for any starter was 5.3 (Mark Buehrle). In the minors, Gibson averaged 8.0 K/9.

The story is the same for almost every Twins starter. Gibson, Mike Pelfrey, Ricky Nolasco and Phil Hughes all have strikeout rates that are below their career norms, so as long as they're healthy, you'd expect upticks across the board.

It's not just strikeouts. Take a look at Hughes. Even though he's throwing strikes at a ridiculous rate similar to last year, his results have been much worse, as he's given up 56 hits and nine homers in 44 innings. Although he's been hittable and homer-prone at times in the past, it's never been to this extent. His BABIP (.326) is 25 points higher than his career norm, and his HR/FB ratio (15 percent) is sixth-highest in the AL.

If he keeps doing his thing, those unlucky numbers should become a bit more neutral over time.

They keep the ball in the yard.

Hughes has served up nine homers, and will likely continue to be somewhat susceptible to the long ball as an extreme fly ball pitcher. Tommy Milone coughed up five homers in 22 innings before being sent down. The remaining four Twins starters, though, have allowed only seven home runs in 120 innings.

For most of these guys, that's par for the course. Gibson, who creates a strong downward plane on his sinker delivered from a 6'5" frame, has allowed only 22 homers in 273 MLB innings. Pelfrey has never been homer-prone, yielding 90 in 1107 career frames. Trevor May was taken deep only four times in 18 starts at Triple-A last year. Nolasco is a wild card, given the way he's been throwing, but he has averaged less than one home run allowed per nine innings dating back to 2011.

When you're not giving up the big hits, you have much more margin for error.

Reinforcements are waiting.

When the Twins have needed to reach down to Triple-A for help in recent years, too often they've come up with pitchers like P.J. Walters and Pedro Hernandez who simply weren't big-league material.

Presently, their top option at Rochester is Milone, who has a proven MLB track record. Even with Alex Meyer completely out of sorts, there are intriguing hurlers alongside Milone in that rotation, like Taylor Rogers (2.84 ERA) and Pat Dean (1.93 ERA).

Meanwhile, Jose Berrios is busy in Double-A making his case for a midseason promotion to the Twins, where he would instantly become the rotation's most talented and electric arm.

And, of course, Ervin Santana will return from his suspension in July.

What do you think? Can the Twins rotation remain in the Top 10 in ERA through the end of the season, or do you expect things to unravel?

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Looking for more great Minnesota Twins content? Twins Daily has you covered today...

* Parker takes an in-depth look at the team's increase in deployment of the shift under Paul Molitor.

* Seth recaps Tuesday in the minors, where a pair of Maxes had big days.

* Off the Baggy says that with Aaron Hicks in the mix, the outfield of the future is beginning to take shape.

* Now that Hicks has been promoted, who might be next in line? Seth explores.