Angels ace Garrett Richards needs more tests to determine cause of his biceps injury

Ailing Angels right-hander Garrett Richards underwent a second MRI examination Thursday in Southern California, General Manager Billy Eppler said. On the disabled list with a biceps strain uncovered by an April 7 MRI exam, Richards reported a continued lack of strength within the muscle, which prompted the additional testing.

The results on his cervical spine ruled out cervical disc or brachial nerve issues, according to Eppler. Still, the need for more tests and the dearth of answers for what he is feeling are cause for concern. The 28-year-old Richards is the anchor of the Angels’ rotation.

“We will continue to evaluate him on a daily basis,” Eppler wrote in a text message.

Returning from a rare stem-cell treatment that repaired his torn elbow ligament last May, Richards exited his first start of the 2017 season with what was first diagnosed as a biceps cramp, and eventually as a strain. Sources said he had irritation in the nerve within the muscle.

He said he hoped to be pitching this weekend in Kansas City. Instead, he has remained in Orange County for this seven-game road trip, and there is no plan for him to resume throwing on a particular date.

“I don’t think anything else is planned,” Manager Mike Scioscia said. “We’re moving in the right direction.”

Trout’s takeover

It took fewer than two weeks for Mike Trout to emerge once again as the most valuable player in baseball. Both fangraphs.com and baseball-reference.com’s Wins Above Replacement calculations had Trout tied or alone in the lead as of Friday, for the first time this season.

Since his first full season in 2012, Trout has been worth 47.8 wins per fangraphs.com and 48.9 per baseball-reference.com, which use slightly different methods to produce the figures. His totals are 25% and 29% better than the next-best player, Dodgers ace Clayton Kershaw.

Short hops

The Angels purchased the contract of right-hander Deolis Guerra from triple-A Salt Lake and flew him to town Friday to replace right-hander Daniel Wright on the roster. Wright was designated for assignment after he logged four innings Thursday. Guerra spent most of 2017 in the majors and recorded a 3.21 earned-run average in 53 1/3 innings. …Jefry Marte started Friday at first base and has started over C.J. Cron on all three occasions the Angels have faced a left-handed pitcher. When Luis Valbuena is activated from the 10-day disabled list, he’ll presumably play against right-handers, which could force Cron’s demotion to triple-A.

pedro.moura@latimes.com

Twitter: @pedromoura