In his first news conference this season, LSU coach Paul Mainieri waxed poetic about his veteran ballclub, led by four upperclassmen who spurned a professional contract in order to return for an Omaha run.

Those players — Junior Greg Deichmann and seniors Kramer Robertson, Cole Freeman and Jared Poché — were christened the “Fab Four” by Mainieri that day. They have largely lived up to the nicknamed, leading the charge as LSU has pushed itself to the cusp of its 18th trip to the College World Series.

There was another Fab Four on the LSU roster, though. Perhaps it’d be more appropriate to call them the Fresh Four.

LSU was expected to at least the super regionals, if not the College World Series. And here they are, getting ready to face Mississippi State in the Baton Rouge super regional, which gets underway at 8 p.m. Saturday.

As much as LSU’s expectations were built on its wealth of returning experience, it’s hard to imagine the Tigers being at this point if not for the contributions of their youngsters.

This did not come as a shock to Mainieri.

“Every year in college baseball, you have to count on freshmen,” Mainieri said. “It’s just the way of the world. There’s not enough depth that you can have on a team with only 27 players receiving scholarship aid.

“The way guys sign professionally after their junior year, you don’t have the depth with people who are waiting in the wings to step in. So every year, I know we’re going to have to count on freshmen. You hope they have the maturity, composure, poise and ability to perform.”

Freshmen Josh Smith, Zach Watson, Eric Walker and Zack Hess have played massive roles for LSU all season, but they’ve taken turns cranking it up a notch in the postseason push.

Watson didn’t crack the starting lineup until midway through the season, but he is tied for second on the team with eight home runs. Half of them came in the Baton Rouge regional — when he went deep twice in one game on consecutive days. He also has solidified LSU’s outfield defense with his speed.

“Zach always showed me that he had extraordinary athletic ability,” Mainieri said. “He can flat-out fly, running-wise. He’s got a strong throwing arm, and what really surprised me is that strength that he has. The ball just jumps off his bat.

“He only weighs 160 pounds, but the ball jumps off his bat just about as hard as anybody besides Greg Deichmann.”

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LSU catcher Michael Papierski (2) celebrates with LSU center fielder Zach Watson (9) after Watson's three run home run in the second inning of Game 1 of the 2017 NCAA Baton Rouge Regional between LSU and Texas Southern, Friday, June 2, 2017, at LSU's Alex Box Stadium in Baton Rouge, La.

Smith, a member of the Southeastern Conference All-Defensive team at third base, enjoyed a particularly loud weekend at the plate, going 5-for-9 in the regional with three doubles, a home run and four RBIs.

Though he’s played fine defense at third base this season, Smith will likely slide over to shortstop next year. Mainieri thinks he’s just beginning to show what he’s capable of.

“I don’t think there’s any question that Josh Smith, from the time he walked onto this campus, was ready to play for LSU,” Mainieri said. “There were some things he needed to learn, some things he needed to change, but I think he’s done a pretty doggone good job for us offensively and defensively.

“He wanted to play at LSU his whole life, he got that opportunity as a freshman, and I think he’s made the most of it. He’s going to have a nice career here.”

For the second consecutive week, LSU handed the ball to Eric Walker with a championship on the line, and for the second consecutive week, the Texas native was untouchable.

After 7.2 pristine innings against Arkansas in the SEC tournament championship game, Walker was even better against Rice in the regional final. He left the field after eight shutout innings, and he got a standing ovation for the second straight week.

“The only question I had with Eric (before the season) is whether or not you can win consistently in the SEC without throwing a fastball in excess of 90 miles an hour,” Mainieri said. “But Jared Poché had proven that could happen, and I thought he showed us a lot of the same qualities as Poché.”

Then there's Hess. The tall and fiery right-hander started the season as a midweek starter, but when it became clear that LSU’s bullpen was one of its weak links, he adapted to that role and excelled.

Hess was the only LSU pitcher to make multiple appearances in the regional, and it wasn’t hard to see why. He was superb, striking out seven in three innings. He closed out the regional by striking out back-to-back hitters with the bases loaded and the tying run in the on-deck circle.

“When we moved Hess to the bullpen, it was something that made our bullpen strong enough to be a championship caliber team,” Mainieri said. “He’s played a pivotal role out there.”

It seems safe to say LSU’s chances of reaching Omaha, Nebraska, are as dependent on the performances of its freshmen as they are the performances of its established veterans.

Of course, when one goes well, the other usually follows suit.

“When you really think about it, it makes it easier with the veterans around,” Walker said. “It really takes the pressure off you. ... Sometimes you can feel a little more pressure to perform. With the guys leading the way that are older, it makes it a lot easier just to quietly do your thing.”

Follow Luke Johnson on Twitter, @ByLukeJohnson.