Yankees fans are familiar with openers.

When the Tampa Bay Rays successfully piloted the strategy in 2018, it led to much hand-wringing among baseball purists. Last winter, talking heads lamented the death of starting pitchers.

Those complaints were premature.

Only a few teams have used an opener more than a handful of times. Only three have had any success -- the Rays, Yankees, and Angels. It turns out a team needs very specific personnel for the opener to work.

An opener is basically a reliever used out of order. Instead of turning to a middle reliever in the sixth inning, they're used as a faux-starter to begin the game. The primary pitcher (also referred to as a follower, main or bulk pitcher), enters in the second or third inning.

The point of the strategy is to minimize the number of times the primary pitcher faces the top of the lineup. Research clearly shows that pitchers decline in effectiveness with each time they face a hitter. This is especially true of the talented batters at the top of a lineup.

As the Rays have aptly demonstrated over the last season and a half, the opener strategy can save runs. Reliever Ryne Stanek has made 22 "starts" for the Rays this season. His usage is a big reason why the club has a 45-35 record.
Stanek is an above-average reliever who features a 98-mph fastball, over a strikeout per inning and a 2.47 ERA. As an extreme fly ball pitcher, he has predictable strengths and weaknesses. Since it's relatively easy to optimize his matchups, the Rays can cherry pick when to use him and when to go straight to the primary pitcher.

For the opener to work, a few conditions must be met. A team must have a surplus of quality relievers. The opener has to be sufficiently talented to reliably retire top-of-the-order foes like Mookie Betts. He should be similar in quality to a setup man.

Primary pitchers often throw five or fewer innings. That means in addition to the opener, a typical collection of setup men is required to bridge from the sixth inning to the closer. As you can imagine, it's difficult to consistently run an opener without an eight-man bullpen stuffed with quality relievers.

The Yankees meet these conditions, which is why they've been able to turn Chad Green into the best opener in baseball.

Aroldis Chapman is fronted by Zack Britton, Adam Ottavino and Tommy Kahnle. That quartet -- along with an early-season slump -- has left Green out of the late-inning role he earned last season.

Green has risen to his new job with aplomb. Although his seasonal numbers, including a 6.49 ERA, appear subpar, most of the damage was incurred prior to a demotion in mid-April. Since returning on May 12, he's performed superbly, posting a 2.41 ERA with 13.98 K/9 and 0.96 BB/9. Seven of 15 appearances have come as an opener. In those 10 2/3 innings, he has a 2.53 ERA, 14.34 K/9, and 1.69 BB/9. This elite performance early in the game greatly increases the Yankees' odds of winning.

To date, the only other notable openers in the league are Stanek and Cam Bedrosian of the Los Angeles Angels. Stanek, whom we already discussed in some detail, cannot match Green's ability to induce strikeouts and prevent hits. Bedrosian, a ground ball pitcher with a 2.41 ERA, 10.37 K/9, and 3.86 BB/9, also lacks Green's ceiling.

While all three pitchers have posted similar ERAs in the opener role, Green is the only one who has done so in a luck-neutral way. Advanced ERA estimators and projection systems believe Stanek and Bedrosian will post anywhere from a mid-3.00s to mid-4.00s ERA going forward. By contrast, Green should have little issue maintaining a sub-3.00 ERA.

Injuries to Domingo German and Jonathan Loaisiga -- both of whom are on the mend -- forced New York to explore using Green as an opener. Nestor Cortes has filled in ably as a primary pitcher who comes in after the opener. Of Green's seven "starts," Cortes has followed him five times. The Yankees have won them all.

With German scheduled to return within the next two weeks, Green might bounce back to a middle relief role. However, his emergence as the top opener in the sport could encourage manager Aaron Boone to stick with this winning formula.

Perhaps German will soon find himself following Green? Only time will tell.