TRENTON – After a surprise assignment to Tampa to begin the year, Mikey O’Brien is back with Trenton.

The right-hander made 19 starts with the Thunder last year, including a pair on the team’s run to the Eastern League Championship Series. So it was a bit of a shock to see him re-assigned to the Florida State League out of spring training.

In a half-dozen turns with Tampa, O’Brien was 1-2 with a 4.39 ERA. He surrendered 33 hits in 26 2/3 innings. He fanned 34 and walked eight.

“The fact of the matter is he is coming,” manager Tony Franklin acknowledged Tuesday evening. “What we’re going to do with the rotation I don’t know yet. We’ve got eight guys on our staff who are capable of starting, so we don’t know what we’re going to do.”

And while an eight-man rotation is obviously not up for discussion, the scenarios to get O’Brien into the rotation are plentiful.

If the Thunder choose to stick with a six-man rotation, they could simply slide O’Brien in on Friday, which would normally be Francisco Rondon’s turn to pitch. Rondon, however, hasn’t had  a great time as a starter – he’s sporting a 7.16 ERA in six starts – and Franklin admitted before Tuesday’s game that his return to the bullpen is one of the options that has been discussed with the organization’s pitching people.

Even if Rondon is removed, that still leaves enough arms – O’Brien, Jose Ramirez, Nik Turley, Zach Nuding, Matt Tracy and Caleb Cotham – to form a six-man rotation if the organization so chooses. But one of the six-man rotation’s original purposes was to help limit innings for guys like Rondon, who’d been a reliever for nearly all his career.

Another guy whose innings limit for the season was on the lower side is Cotham, who pitched a career-best 101 1/3 frames last season. That low total means he’s probably not ready for a full starter’s workload – Shaeffer Hall and Brett Marshall each threw more than 150 innings, plus playoffs, for last year’s team – this season and will likely have to have his amount of work ramped down at some point.

His name has been bandied about for a possible trip to Triple-A Scranton over the last few days, and even he acknowledged on Tuesday that he doesn’t quite know where he’ll be doing his pitching in the next couple of days.

And because his situation is uncertain, so is the Thunder’s.

“I think Mikey’s going to come and start for us. That’s what my understanding is,” Franklin said. “Whose place he’s going to take and exactly what we’re going to do with the rotation – whether we’re going to leave it as a six-man, if we’re going to have an eight-man or if we’re going to have a five-man, I don’t know yet.”

This much is clear: O’Brien is on his way to Trenton, and he’s going to start. Whatever happens around him remains to be seen.

NOTES: The Thunder still have not received final word on the severity of third baseman Rob Segedin’s injury. That should come over the next couple of days. … In addition to Billy Hart, the Yankees’ assistant director of baseball operations, roving infield coordinator Carlos Mendoza and pitching coordinator Gil Patterson were on hand on Tuesday. Mendoza played for the Thunder from 2007 until 2009.