But what seemed like such a logical move has had a major impact for LSU's defense – maybe even on par with the now famous tweak Mainieri made in 2009 when he inserted Austin Nola as the starting shortstop midway through the season.
Back at the spot where he started all 56 games as a freshman, Jones has been dazzling. He enters the NCAA Tournament with only four errors in 202 chances.
"I like playing in the infield and I was glad when Coach asked me to move back in there," said Jones, a potential candidate to take over for Nola at shortstop next season. "I was OK playing in the outfield, but I've always been an infielder."
As much as Jones shrugged off this impact, his teammates were more effusive in describing he has helped shore things up.
Nola gushed about Jones the way his teammates often do about the steady shortstop. First baseman Tyler Moore said Jones has made him a better defensive player.
"As an infielder, when the ball is hit to your other infielders, you want to feel like it's an automatic out," Nola said. "He's played really well defensively and has showed a lot of poise. He gives us some extra confidence on the infield and that's huge when you're playing close games."
That's the kind of difference Mainieri had in mind when he made the switch.
Early in the season Casey Yocom was the starter at second base, and while he was solid, there were some balls he couldn't get to. Mainieri said he realized the Tigers were headed toward a lot of close games – he was right, LSU has played 23 one-run games – which magnified every potential out.
"In a low-scoring game, one defensive play could make the difference in that game," Mainieri said. "I thought JaCoby did a good job in center, but I thought he could be a great second baseman. I thought he was a difference-maker at second last year."
It certainly seems like Jones has picked up where he left off.
With him back on the infield, the Tigers have fielded at a .980 clip this season despite a revolving door at first base at times. Like Jones, Tyler Moore and Mason Katz have solidified that spot.
But it's Jones who has anchored the right side of the infield.
"He gets to everything," Nola said. "His range is unreal out there and that's what Coach wanted when he put him back there. He's pretty smooth.
"You can't give up on a ball can't or ever take anything for granted. He makes the tough plays look easy. You better not hit it within a 10-foot range of him because he's going to get to it."
Rhymes, Gausman earn All-American nods
Collegiate Baseball magazine tabbed LSU stars Raph Rhymes and Kevin Gausman as 2012 All-Americans on Thursday.
Rhymes leads the country with a .459 batting average and is coming off a memorable week when he was voted the SEC Player of the Year.
Gausman was a first-team All-SEC pick and will take a 10-1 record and 125 strikeouts to the mound Saturday in the second round of the Baton Rouge Regional.
The Tigers are the only team in the country to land two players on the first unit. This year marks the first time since 1998 that LSU has featured a pair of first-team All-Americans (Eddy Furniss and Brad Cresse).
Heroes wanted: Tigers open NCAA play ON DECK: LSU Regional
ON DECK: LSU Regional