Who is the current ace of aces in Major League Baseball? And which "aces" wouldn't even sniff the starting rotation for the likes of the Astros, Dodgers, Padres and Yankees?

The tricky first step in this process was deciding on the ace of each staff. For 23 of the 30 franchises, it wasn't a tough call. However, a fair amount of hemming and hawing and emailing with colleagues took place regarding the other seven.

Those decisions didn't impact the ranking, though, considering how little separation exists between the candidates for that ace spot. For instance, whether you deem Walker Buehler, Tony Gonsolin, Clayton Kershaw or Julio Urias to be the ace of the Dodgers staff, he'll land somewhere in the Nos. 10-15 range. (Spoiler alert: We went with Kershaw and also defaulted to the "old guard"—Adam Wainwright, Justin Verlander, etc.—anywhere that it made sense to do so.)

One important criterion: The pitcher must have made at least seven starts this season in order to qualify. With apologies to Jacob deGrom, Stephen Strasburg, Lance Lynn, John Means, Tyler Glasnow, Lance McCullers Jr. and others who fall short of that threshold, you at least temporarily lose your ace status when you can't manage to pitch in 10 percent of your team's games.

Once the 30 aces were chosen, the ranking is based on a combination of dominance in the current season and past track record, with current season success generally taking preference over previous accolades.

Unless otherwise noted, statistics are current through the start of play Sunday, June 19.

Nos. 30-28: Patrick Corbin, Jose Quintana and Tyler Wells

30. Patrick Corbin, Washington Nationals

• 3-9, 6.59 ERA, 1.78 WHIP, 6.4 K/9, 2.1 K/BB

From 2017 to 2019, Corbin was easily a top-10 pitcher in the majors. He had a 3.47 ERA, averaging just over 220 strikeouts per year, and he was an indispensable asset for a World Series champion in the final season of that three-year arc.

But he has gone from indispensable to darn near unusable. His 3.25 ERA in 2019 steadily ballooned to 4.66 in 2020 to 5.82 last season and now to 6.59. His slider was once one of the most unhittable pitches in baseball, but opponents have been teeing off on it as of late. As if Stephen Strasburg's gargantuan contract and all the deferred payments to Max Scherzer aren't bad enough, the Nationals are paying Corbin $23.4 million this season, $24.4 million next year and $35.4 million in 2024 for his rapidly deteriorating services.

29. Jose Quintana, Pittsburgh Pirates

• 1-4, 3.66 ERA, 1.33 WHIP, 7.7 K/9, 2.5 K/BB

Quintana used to be one of the most durable starters in the game. From 2013 to 2019, he was tied with Jon Lester for the most games started (224) and did so with a FanGraphs WAR (26.6) that ranked 11th among pitchers.

However, after 2020 and 2021 campaigns that were both injury-riddled and ineffective, the offseason market for Quintana was nonexistent. The 2016 All-Star ended up on a one-year, $2 million deal with the Pirates, where the primary goal seemed to be that he provide some veteran leadership in what is otherwise a young rotation.

He has been better than expected, though, and might be a hot commodity ahead of the trade deadline. Quintana has cooled off over the past month, but he had a 2.19 ERA after seven starts and has yet to allow more than four earned runs in a game.

28. Tyler Wells, Baltimore Orioles

• 4-4, 3.62 ERA, 1.07 WHIP, 5.4 K/9, 3.0 K/BB

Wells missed all of 2019 following Tommy John surgery and all of 2020 because there was no minor league baseball that year. He then spent the 2021 campaign in the bullpen for the O's, even making four saves in September. But no one knew what to expect from Wells as he transitioned back into a starting role for the first time in nearly four years.

After a rocky start, he has been pretty darn good. In nine starts since the beginning of May, Wells has a 3.09 ERA with four quality starts. He went six scoreless innings against the Red Sox on Memorial Day and relinquished just a solo home run to Teoscar Hernandez in six innings of work against the Blue Jays last week.

It's a small sample size, but Wells might be a key piece in this rotation for years to come.