Upperclassmen beware: with more than 20 games of collegiate experience, the freshmen on the Northwestern baseball team are creeping their way into the lineup and onto the pitcher’s mound.

In the Wildcats’ series against Purdue last weekend, freshmen pitchers started two of four games. Mark Ori racked up a loss on Saturday — his first of the season — and Dan Brauer notched his third win on Sunday.

Ori, who boasts a .321 batting average, also seems comfortable with his role as designated hitter.

“It just comes down to who’s swinging the bat well,” junior David Gresky said. “Ori’s been smoking lately.”

But adding freshmen to the lineup means that veteran players suffering batting slumps rotate out. Senior Travis Tharp and junior Jason Krynski stepped up to the plate on Friday and Saturday but sat on the bench on Sunday.

Tharp’s .207 batting average is down from .283 last season, and Krynski is down to a .125 after hitting .250 in 2002.

“Travis Tharp is the biggest clutch hitter I think I’ve ever had at Northwestern, ” Stevens said. “He’s in a little bit of a tough scenario right now, and we’re trying to get the edge back.”

The coach gave the same reasons as to why Krynski was replaced with freshman Anthony Wyklendt.

“There’s a lot of guys who are playing really well, but we had to shake things up and felt we needed to move some guys to different positions to stimulate the offense a little bit.”

With five conference series remaining this season, Tharp and Krynski have plenty of time to fire up their bats again.

“By the time push comes to shove in this conference race, they will be right back to doing all the things we’re used to seeing them do,” Stevens said.

Raise the Roof: When Gresky smacked a ball deep over right field on Friday, he wasn’t expecting it to hit the roof of Welsh-Ryan Arena.

“There were wind gusts, so on a normal day I don’t think it would have gone all the way,” Gresky said.

With the high-flying homer, the right-fielder became only the third player in NU coach Paul Stevens’ 16 seasons to hit one onto the roof. The other two hitters were Hall-of-Famer Dave Winfield, who played for the Golden Gophers, and Kirk Gibson, who played for Michigan State.

A sign of things to come? Gresky said he still has some work to do first.

“Those guys are probably all Hall-of-Famers in the major leagues right now, and I’m hitting .250, .260 right now, so I don’t know how good of a sign that is,” Gresky said.

Wild Thing: J.A. Happ was unusually wild in the first game of Saturday’s doubleheader, walking the bases loaded once, giving up five free passes total, and throwing one wild pitch. The sophomore had control problems for much of the game, only throwing five first-pitch strikes in his 5 2/3 innings of work. Purdue took advantage of his mistakes, tagging the most recent Big Ten Pitcher-of-the-Week for nine hits and five runs (three earned) in what he considered the “worst game I’ve had in my career.”

“That wasn’t your typical J.A. Happ appearance yesterday, ” Stevens said. “I don’t know who that guy was in that uniform, but I don’t think we’ll see him much this year.”

When Happ did get the ball over the plate, he was near unhittable, fanning seven Boilermakers, six swinging and one looking.

The lefty threw 118 pitches, 70 for strikes, in his outing. Stevens left him in, hoping he could work out of his jams.

“That’s a few too many pitches,” Stevens said.

But the first-year starter’s pride was hurting more than his arm after his workhorse performance.

“My arm is a little tight, but it’ll be fine,” Happ said Sunday.

Around the Horn: Before the start of the fourth inning in game one of Saturday’s doubleheader, the PA announced the start of the “Maggiano’s Home Run Inning.” Less than 30 seconds later, Dan Pohlman knocked the first pitch he saw out of the park to lead off the inning and won a lucky fan a $25 gift certificate to the local restaurant … In attendance at game one of Saturday’s doubleheader with his daughter was former NU star and current St. Louis Cardinal Joe Girardi. The backup catcher, who lives nearby, is currently on the DL with pains in his right side and upper back and has not played a single game this season … Brandon Ackley, NU’s hits and average leader last season, is currently mired in an 0-13 slump which began on April 6 at Michigan State.