During a 2019 appearance at the State Fair, Derek Falvey, Twins president of baseball operations, explained how difficult it is to develop quality starting pitching.

"How many starting pitchers in the minors debut in the majors as a starter?" he asked an intrepid interviewer. When the interviewer appeared to be stumped, Falvey said, "Fifty percent."

Jhoan Duran is an example of the realities of pitching development. Once looking like a future front-line starter, he now has to settle with becoming one of the best closers in Twins history. If you have a quibble with the notion of Duran eventually out-performing Twins closing greats Rick Aguilera and Joe Nathan, then we can settle for Duran being one of the game's most feared relievers. You don't want to face a guy whose fastball has topped out at 104 mph this season and throws a unique pitch called the "splinker."

As recently as 2021, Duran was starting at Class AAA St. Paul. He made 80 starts in the minors, 32 while with the Twins organization. Duran was the most highly touted of three prospects the Diamondbacks sent the Twins for Eduardo Escobar in 2018.

Duran was throwing in the mid-90's then, occasionally touching 97 mph while mixing in a slider. While at Class A Cedar Rapids, he responded well to the Twins' suggestions. He junked his slider. He changed the grip on his split-fingered pitch, which gave it sink. That's the pitch he calls the splinker. He became mechanically sound, which allowed him to increase his velocity and maintain it. Instead of a slider he learned to throw a curveball, a pitch that has become one of the best in baseball. He got a 49.7% swing-and-miss rate with his curve last season. This season, he's third among relievers with a 42.9% rate.

Pairing a heater that hit 104 mph during Wednesday night's win over Seattle with a nasty curveball is a challenge to hitters. Mix in an occasional pitch no one else throws, and it's unfair. He has three quality pitches, the required arsenal for a starting pitcher.

Think about it. If Duran would have stuck as a starter, the Twins would have not had as much motivation to deal for Pablo López during the offseason. Luis Arraez would still be here and ... oh, never mind.

Duran could never get stretched out enough to handle a starter's workload. Plan B has been a fantastic development for the Twins, who have solidified the position now for years to come.

He began last season in the Twins bullpen and immediately thrived. On Sunday, he pitched for the third straight game as the Twins defeated the Athletics. It was the first time in his career he pitched in three consecutive games, and he needed 47 pitches to do so. If the Twins' sputtering offense can find a way to gain leads through eight innings, they have one the best ninth-inning options around. He entered Tuesday's game in Seattle with a 2.17 ERA and 15 saves.

Duran, with 23 saves since the start of 2022, should move into the Twins top 10 in career saves sometime next season. Then it is a matter of staying healthy. Nathan, whose 260 saves are the most in club history, was a college infielder who didn't become a closer until he was 29. Aguilera, next with 254 saves, wasn't a full-time closer until he was 28. Duran hasn't turned 26 yet and already is dominant. If he can pitch into his late 30s like Nathan and Aguilera, Duran will join them at the top of the Twins' closers list.

One thing Duran has in common with Nathan and Aguilera: There is a "this game is over" feeling when he enters.

Part of me wishes Duran would have been able to stick as a starter, because he could have been the Twins' first real ace since Johan Santana. The other part of me says "shut up and enjoy what Duran has become."