Early in 2023, Mookie Betts made the surprising in-season transition from right field to the middle infield for one simple reason: Because the Dodgers needed him to. Between injuries to Gavin Lux, Chris Taylor and Miguel Rojas, and the struggles of rookie second baseman Miguel Vargas, Betts found himself making 62 starts at second base and a dozen more at shortstop, as well as 77 more in his usual right-field spot.

It went incredibly well. Betts had an OPS of .970 or better at all three spots. He became the first player in AL/NL history to play at least 15 games at both middle infield spots and the outfield while also slugging .500. It was a huge part of Betts' NL MVP Award case, before a late-season slump allowed Ronald Acuña Jr. to pull away with it.

If it seemed at the time like a heroic response to an emergency situation, we might eventually look back upon it as the beginning of the second phase of Betts' likely Hall of Fame career. In 2024, it won't be that Betts will be playing second base because the roster situation demanded it. It’s that he’ll be playing the keystone regularly because it’s just the plan now, as had been hinted at for weeks, and which manager Dave Roberts was somewhat surprisingly concrete about on MLB Network live from the Winter Meetings on Monday.

“It’s pretty safe to say that number 50, Mookie Betts, is going to be our everyday second baseman,” Roberts said.

It's borderline unprecedented to see something like this, a player moving from right field to second base full-time this late in a career, given that since 1947, there’s only 25 players, Betts included, to have played 100 games in an entire career at both second and right field. None of them did it the way Betts will.

Of the other 24, most (like Tony Phillips or Mark DeRosa) were just true utility players. Some (like Lee Lacy) moved from second to the outfield. The only somewhat similar case was, believe or not, Pete Rose, who spent his first few years at second base, moved to the outfield at 26, and came back to play mostly third base at 34 until becoming a first baseman at 38, and even that isn't really the same.

Historical relevance aside, it’s not hard to see why Betts' move seems to be more of a most-of-the-time move than last year's was. (We hesitate to say full-time, since this hardly closes the door on appearing in right field again, though Roberts referred to it as an “as-needed” situation.) That's in no small part because by all indications, it makes Betts happy. After all, this is a player who was an infielder in the Red Sox's system before moving to the outfield in deference to Dustin Pedroia.

“I’ve never considered myself a right fielder,” Betts said in July. “I just play right field. I’ve always considered myself a middle infielder.”

“Now you get a happy Mookie Betts,” Roberts said on Monday, “a guy that can post and play 160 games, it makes the Dodgers much better. It’s pretty much a no-brainer.”

If this is what he is now, primarily a second baseman, then the offensive benefits are clear, because it’s simply harder to find offense from a second baseman than a right fielder – a fact which was as true in 2023 (the OPS from 2B was .724, compared to .754 from RF) as it’s been for the entire history of the sport. That's been true every year but one dating back to World War I, in fact, aside from a fluke in 2016. As everything else about the sport changes, this does not. It's hard to find hitting at second than right field.

Thus: Betts, second baseman, is more valuable to the lineup than Betts, outfielder.

Put it this way: Betts had a 163 OPS+ last year, making him 63% above league average as a hitter, which is excellent no matter what position it’s coming from. Dating back to the start of integration in 1947, that would have been the 48th-best hitting year by a right fielder, yet it would have been the fifth best by a second baseman. We’re oversimplifying a bit here, but the idea is that it’s harder to play second base than right field, so equal offense is more valuable from second base; you can read all about positional adjustments if you are so interested.

It means, looking ahead to 2024, that Betts was projected to be the fourth-best hitting right fielder – which is, again, extremely good – but the best, by far, second baseman. Unlike last year, when he mostly played second against righties and right field against lefties, he’s expected to play second against all comers.

So it’s a boost, though not one without repercussions. It means Vargas and fellow up-and-comer Michael Busch have to learn to play positions that aren’t second, or else find employment elsewhere, which might be more of a solution than a problem, given that a trade for a starting pitcher has always seemed likely.

It means that the outfield depth chart without Betts is currently James Outman (lefty), Heyward (lefty) and Taylor (righty), which absolutely demands an outfield upgrade, preferably a right-handed one. That's part of the value here, too; it's easier to find a right-handed-hitting outfielder than a second baseman, as a quick look at the free agent list will confirm.

But: What about the defense?

It might, you’d think, seem like a waste to take an all-world defender like Betts and take him out of his most valuable position. You don’t really need numbers to validate the eye test and the six Gold Gloves to show that Betts has been an elite right fielder, but we have the numbers, and they back it all up. Because his career predates Statcast, we can look at Defensive Runs Saved and find the best outfielders from 2014-23, and we’ll find that Kevin Kiermaier is first (+165 DRS), with Betts second (148). As you'd expect: Fantastic.

But 10 years is a long time, and there are indications that the Betts of 2024 is more of a good outfielder than a great one. Looking at his Statcast metrics, you can see that it's been some time since he rated as truly elite defensively in right, and his speed has fallen from excellent to merely average over the past three years -- none of which is a surprise for a player in his 30s who spent most of 2021 dealing with a hip injury. It's not, at all, to say he can't or shouldn't play right field. It's just that as time has gone on, he's not quite the right-field legend we remember. (Heyward, for what it's worth, rated as a better fielder with a stronger arm last year.)

As a second baseman, Betts rated as -1 Out Above Average, or essentially average, which is considerably better than it sounds. Being "average" at a position you're moving to in-season and haven't regularly played in years is quite the accomplishment, and it's miles better than the -7 OAA that Vargas had posted in half a season. It's not all that hard to expect that or better given a full winter of preparation, plus the experience gained last year.

But there's something else, too, noted by Roberts that might have been buried in the headlines. “He’s a Gold Glover out in right field, but I think that when you’re putting together a roster, and someone who can be so offensive at second base, you can get more games out of him if he is playing second base.”

It matched what he'd said in July, noting that "I know Mookie likes being on the dirt. It keeps him more fresh, keeps him involved and keeps him more dynamic."

Even on Monday, Roberts implied to reporters that he thinks part of Betts' huge 2023 at the plate was related to less time having to run around the outfield, a stance echoed by Betts himself in July.

"That is one of the benefits of playing more infield than ever before as a Major Leaguer," he told the Los Angeles Times. "All those long jogs from right field to the dugout? Tracking all those balls in the outfield? All the way out [to right field] and back 18 times. Then instead of me taking three steps to the right, backhand, boom, throw to first, you’ve got to take 30 at a full sprint. That in itself is an extra load.”

Betts is a star no matter where he plays, and in part his value in 2023 was from his willingness to play anywhere he was needed. But everyone involved seems to think that this move is going to let him play more and keep him fresher, and whether that's true or not, there's something to be said about keeping a star happy and the simple math of where it's most valuable to have elite offense.

Just about no one had done what Betts had done last season. He might be the first to make the move full-time like this, too.