Lowe is getting ready for his opening duties

Guesstimates are sufficient this time of year, Derek Lowe figures.

The right-hander knew he threw plenty of first-pitch strikes during his 4 2/3 -inning start in the Dodgers’ 5-0 loss to the Cleveland Indians on Sunday. That was good.

He knew he threw a handful of poor changeups, including one on a full count to David Delucci in the fourth inning that resulted in Lowe’s first walk of the spring. That wasn’t so good.

He knew the Indians repeatedly pounded his sinker into the ground, and he knew he threw several wicked curveballs. No problem there.

“I felt good about everything except the changeups,” he said.

Above all, Lowe was aware that he has only two more spring starts before he takes the mound opening day at Milwaukee. No guesstimate there.

“It’s getting close,” he said. “I’ll go 90 to 95 pitches Friday, maybe try to go the whole way. Then I should feel like I’m ready. The last start will be a tuneup.”

As for the walk after 13 1/3 innings without issuing one, he was mildly upset, then philosophical.

“It was good to get it out of the way,” he said. “If I didn’t walk anyone all spring, I’d walk the first guy I faced opening day.”

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Although Brett Tomko has thrown no more than three innings in any outing, he is on track to begin the season as a starter.

The lengths of outings are determined by pitch counts, not the number of innings a pitcher throws. Tomko threw more than 70 pitches in his last start, and pitched a fourth inning in the bullpen after a recent start to hike his pitch count.

“He’ll be up over 90 by the time the season starts,” Manager Grady Little said. “We’re on a strict pitch count with every pitcher.”

Billingsley’s new role

Chad Billingsley doesn’t even pretend he’s thrilled about moving to the bullpen. But he understands that the best way to get into the starting rotation is to pitch well in relief.

His one inning against the Indians was fraught with the same problems that cost him a chance at becoming the No. 5 starter. He threw a wild pitch after giving up a leadoff single, issued a one-out walk and gave up a run on a sacrifice fly.

“I’m learning a new role,” he said. “I have to be ready at all times. I have to warm up quicker and just get loose instead of worrying about where the pitches are going.”

He’s yet to pitch on consecutive days.

“I did it once in high school,” he said. “I threw seven, then went three the next day. But I had a rubber arm then.”

Impressive strikes

Left-hander Tim Hamulack and right-hander Chin-hui Tsao each struck out Indians slugger Travis Hafner, making another solid impression on Little. Hamulack hasn’t given up a run in six spring innings, and Tsao has given up one run in six innings.

After striking out Hafner in the fifth inning, however, Hamulack displayed the inconsistency that plagued him last season. He gave up two consecutive singles, the second a result of his failure to cover first base on a ground ball to James Loney.

Tsao pitched a perfect inning, striking out two.

Neither reliever is expected to make the opening-day roster, but both are in the Dodgers’ plans.

Hamulack made 33 major league appearances last season, and Little said he is “much improved.” Tsao was signed to a minor league deal after the Colorado Rockies gave up on him following several injury-marred seasons, but his arm not only is healthy, it’s live. The pitch that struck out Hafner was clocked at 95 mph.

Errors of their way

Lowe was victimized by errors from third baseman Andy La Roche and shortstop Chin-Lung Hu -- the likely left side of the triple-A Las Vegas infield. La Roche has seven errors this spring.... Injured outfielder Jason Repko could return in about three days, Little said, tempering speculation that he would begin the season on the disabled list and open a roster spot for Larry Bigbie or Wilson Valdez. Repko has been sidelined because of a pulled groin.

steve.henson@latimes.com