How did the Twins' rotation go from one of MLB's worst to one of its best?

A year ago through 43 games, the Twins were 27-16 and leading the American League Central by 5.5 games.

Their surprisingly good start, though, was hiding some major flaws. While the overall health of their roster proved to be a major downfall that contributed to a 78-84 finish, the starting pitching enjoyed reasonable health.

It just wasn't very good in a lot of ways.

Fans, the media and sometimes even members of the rotation lamented that they starters weren't given a chance to work deep into games. But that was the plan in a year with a rushed spring training, and it continued as shaky pitchers often struggled when given a chance to face hitters a third time in a game.

The Twins finished the year No. 27 in innings pitched by starters, No. 20 in starters' ERA and No. 23 in starters' strikeouts per nine innings.

Their marks in those three categories this year are a stark contrast: No. 1 in innings pitched by starters, No. 1 in strikeouts per nine innings and No. 2 in ERA.

How, then, did the Twins go from having one of baseball's least effective starting rotations to one of its best this season?

There are a few reasons, as I talked about on Wednesday's Daily Delivery podcast. And the sum total is a team that even at 24-19 — three games short of last year's pace — feels a lot more like a legitimate contender.

Let's take a look at some factors in the improved pitching:

*Better depth: Your pitching will be better when you have better pitchers. It's simple but it's true. The offseason acquisition of Pablo Lopez was particularly important. Even though Lopez has struggled in some recent outings and the price (Luis Arraez) was steep, Lopez gave the Twins a legitimate 1-3 (along with Sonny Gray and Joe Ryan, both of whom have been exceptional this season) and his presence has allowed them to withstand injuries to Tyler Mahle and Kenta Maeda.

*Internal improvement: Ryan is one of several Twins pitchers who spent part of the offseason tweaking his arsenal and improving his velocity at Driveline Baseball in Seattle. That has helped Ryan in a number of areas and has him off to a 6-1 start with a 2.16 ERA.

*Better receivers: The offseason addition of Christian Vazquez combined with a return to health for Ryan Jeffers has given the Twins two catchers adept at handling pitchers. The staff ERA last year when the since-departed Gary Sanchez was behind the plate was 4.27 — almost a full run higher than their 3.32 team ERA this season.

*Improved results have led to more trust: Limited by a rotation that included Chris Archer and Dylan Bundy a year ago — pitchers the Twins didn't want going more than five innings either to preserve health or effectiveness — starters rarely worked deep in games. When they did, the results were often rotten: In 448 plate appearances when facing a Twins starter for the third time in a game in 2022, opposing hitters had a .287 batting average and an .825 OPS.

This year, pitchers are working much deeper as evidenced by the top ranking in starters innings. And the numbers show it is warranted: In 215 plate appearances when facing a Twins starter for the third time in 2023 — about half of last year's number in about a quarter of the games — opponents are hitting just .219 with a .643 OPS, numbers comparable to the first two trips through the order.

Bailey Ober is a good example of this expanded trust. He's thrown at least 5.2 innings in all five starts, including six strong innings in Tuesday's win over the Dodgers, after reaching that threshold in just three of 11 starts last year. And he's allowed just a .480 OPS against him the third time through the order.

Whether the Twins can sustain this pace is a good question. The aforementioned injuries to Mahle and Maeda have left the Twins vulnerable to another injury, as there doesn't seem to be another pitcher as ready to step into the rotation as seamlessly as Ober and Louie Varland have so far.

But this has to give you hope: Against three of MLB's best teams a year ago, the Dodgers, Astros and Yankees, the Twins went a combined 2-15. This year against those same teams, heading into Wednesday's series finale in Los Angeles, the Twins are a combined 7-5.

Excellent pitching is paramount against good teams. That's true in May, and it's especially true in October.