By Bruce Levine–

GLENDALE, Ariz. (CBS) — The  White Sox starting rotation has more clarity after the demotion of right-hander Erik Johnson, the International League Pitcher of the Year in 2015, to Triple-A Charlotte on Monday.

Johnson has made great strides in his ability to get hitters out, as well as handling the mental side of the game, but it wasn’t enough to nab a spot on the Opening Day roster. This move sets in motion a rotation of Chris Sale, Jose Quintana, Carlos Rodon, Mat Latos and John Danks as the regular season nears.

Scott Carroll and Jacob Turner are on the periphery of the White Sox rotation. Neither pitcher has options for the minor leagues left, which means they must make the club out of spring training or go through waivers and be exposed to being claimed by another club.

With the addition of Latos to a one-year deal in early February, the numbers game caught up with Johnson, who will be ready to help the team if a starter is injured or falters in performance.

“Once we had (Latos) signed, it looked like it would be this way unless there was an injury,” White Sox manager Robin Ventura said. “We needed to get Erik stretched out. All these guys who are sent to the minor leagues still must get their work in and get ready for their minor league seasons. They must be ready to help us if we need them. Right now, we need Erik to get ready in case something happens. We don’t have enough innings for him to pitch here now.”

Ventura was confirming that his main starters will pitch twice more in exhibition play before the season opener on April 4 in Oakland. Rodon threw the equivalent of six innings in a minor league game against  White Sox players Monday, and he wasn’t happy with the results. He did get 89 pitches in to build up his arm strength, and some of the outing was geared toward work on subtle nuances of his pitches.

“The last one out wasn’t that great either,” Rodon said. “The arm strength keeps improving, the (velocity) is coming back. I need to hone that in and get some hard fastballs in the zone.”

Pitching coach Don Cooper wasn’t concerned with the below-average performance from Rodon on Monday.

“We were looking to put some guys on base to practice his pick-off motion,” Cooper said. “We were also looking for more and more strikes. The thing with Carlos is we are trying to get better in the first three pitches to hitters. We are looking to get (soft) contact or to get ahead in the count. If we do that, we lessen walks. If we lessen the walks, there will be more balls in play. He can be dominant when ahead on the count. Getting ahead is the key to any pitcher’s success. We are looking for improving pitchers all the way around. Carlos is just 139 (big league) innings into the process. Certainly, there is a lot more to go.”

Bruce Levine covers the Cubs and White Sox for 670 The Score and CBSChicago.com. Follow him on Twitter @MLBBruceLevine.