Then late in Thursday's 5-1 win, the Kansas City ace really heated up. He struck out the side in the sixth and did the same in the seventh before striking out the first batter in the eighth to make it seven in a row. Astro after Astro simply watched the pitches zip past them - five players in that span struck out looking.
Shields finished with 12 strikeouts in eight innings as the Royals completed a three-game sweep of the Astros.
''He moved it around very effectively,'' manager Ned Yost said. ''He was locking guys in, was locking up guys down and away, just had it all going.''
Shields (1-2) gave up one run and four hits, all singles.
''We were pounding the strike zone and getting strike one and getting ahead of the hitters and that's an aggressive team over there and when you get ahead in the count and make your pitches you're successful,'' he said.
His 12 strikeouts were his most as a Royal and the most by a Kansas City pitcher since Zack Greinke also struck out 12 on June 13, 2010, against Cincinnati. The seven straight Ks by Shields were one shy of the franchise record of eight in a row set by Blake Stein in 2001.
The right-hander got back to his winning ways after seeing his nine-game road victory streak snapped in his last start at Minnesota when sloppy defense led to six unearned runs in a 7-1 loss.
Scott Feldman (2-1) yielded four earned runs and nine hits in six innings. It was the first tough outing for the Astros newcomer after he had allowed just one run and seven hits combined in his first three starts.
''It seems like they found a lot of holes,'' Feldman said. ''They're a tough lineup, for sure.''
The Royals were up by two when Alcides Escobar hit a two-run double in the fourth to make it 4-0. Salvador Perez added an RBI double in the fifth.
Kansas City scored 15 runs in this series after managing just five runs combined last weekend while getting swept by the Twins.
The Royals got to Feldman early, with Nori Aoki hitting a leadoff double and later scoring on a groundout by Eric Hosmer.
Alex Gordon, Billy Butler and Mike Moustakas hit consecutive singles to start the second to push the lead to 2-0.
There were runners at second and third with one out in the fourth when Escobar sent them both home with a double to center field.
Aoki singled to begin the fifth before a one-out single by Hosmer. Perez hit a ball that diving center fielder Dexter Fowler missed for a double that scored Aoki and pushed the lead to 5-0. Hosmer was out at home on the play.
Shields allowed a pair of singles in the first inning before retiring the next 10 Astros. Houston didn't have another baserunner until Chris Carter drew a leadoff walk in the fifth. Carter advanced to third on a single by Matt Dominguez, but Dominguez was out trying to stretch it into a double.
Manager Bo Porter was clearly frustrated when asked if he wishes Dominguez would have been more cautious on the play, pausing 18 seconds before answering the question.
''It's just not smart, obviously,'' Porter said. ''And sorry for taking so long to answer the question. I went and asked Matt Dominguez: 'Do you think you're invisible? You are down 5-0 and the ball is right in front of you.' So, to answer your question, no, I don't like it. There was nothing smart about it, and next question.''
Carter scored on a sacrifice fly by Alex Presley to cut the lead to 5-1 later in that inning.
Presley's out was the first of nine straight Astros retired by Shields, including the seven strikeouts in a row.
A single by Presley came with one out in the eighth and Jonathan Villar drew a walk, but Shields ended the threat by striking out Fowler before a fly out by George Springer.
NOTES: The Royals challenged a call after Presley was called safe on a grounder in the second inning. The play was overturned for the third out of the inning. ... Royals LHP Bruce Chen, who was scratched from Thursday's start a day before with a sore back, said he was feeling better on Thursday and expects to be ready to start on Saturday. ... Kansas City OF Lorenzo Cain was placed on the 15-day disabled list with a left groin strain and LHP Justin Marks was recalled from Triple-A Omaha to take his place on the roster. ... Houston selected the contract of LHP Raul Valdes from Triple-A Oklahoma City and optioned LHP Kevin Chapman there before Thursday's game.