Two days after he first tweaked the patella tendon in his right knee, and one day after he returned to the lineup without any extra rest, Royals catcher Salvador Perez was scratched from Wednesday’s game at Coors Field. He experienced a recurrence of symptoms shortly before the game began. “He went out for stretch and felt great,” manager Ned Yost said. “And then after stretching, at the start of B.P., his knee started tightening up right in that spot. With an off-day tomorrow, we wanted to take all the precautions, and give him two days.” Of course, Perez had played the night before. He departed after six innings on Monday. His backup, Erik Kratz, homered twice in the final three innings of a victory over Minnesota. Yet Perez still returned to action. Now team officials must hope his knee injury is not more serious than their initial belief. Perez himself insisted his knee felt “good” on Tuesday. He said he has not experienced pain, but only tightness.