The right-hander quickly finished off a five-hitter for his first shutout in more than six years, backed by four home runs in the St. Louis Cardinals' 10-0 rout over the Cincinnati Reds Wednesday.
"He was making a statement," Matheny said. "He wanted to make sure he gave the appearance he was ready to go. What a great day for him."
Westbrook (1-1) hasn't allowed an earned run in 15 2-3 innings this season, although he took the loss on an unearned run in a 1-0 setback to Barry Zito in San Francisco in his season debut. He relied heavily on a sinker against the Reds with 16 groundball outs.
"It always means a lot when you can finish what you started," Westbrook said. "The ball was in the zone and really moving a lot. I guess I know when I'm good is when I get a lot of ground balls."
The lineup made a statement, too. Jon Jay, Carlos Beltran and Matt Adams homered in a span of seven at-bats off Homer Bailey as the Cardinals took two of three from the NL Central champions after Cincinnati stunned them with a nine-run ninth in the home opener.
"It's a great point about resiliency," Matheny said. "They certainly showed a different brand the last two days."
Matt Carpenter added a two-run homer on a four-hit day. Adams homered for the second straight game and added an RBI double and walk.
The Cardinals have dominated the Reds at home the last decade, losing just three of 28 series with two splits. They outscored them 15-1 the last two games of the series and the Reds were shut out for the first time in the finale.
"I was hoping this would be different this time especially after that first night," Reds manager Dusty Baker said. "The thing about it is their pitching really shut us down."
Westbrook (1-1) pitched his first shutout since Aug. 9, 2006, against the Angels when he was with Cleveland, and this was his 15th career complete game. He held the Reds hitless in six at-bats with runners in scoring position, and contributed his 11th career RBI with a single in the seventh for St. Louis' final run.
"It was a perfect storm," said Joey Votto, one of the few Reds with much success, going 2 for 3 with a walk. "He didn't surprise us because he definitely has that capability."
Bailey (1-1) had gone 23 straight shutout innings -- including his no-hitter against Pittsburgh last season -- before the Cardinals broke open a scoreless game with four runs with two outs in the fifth.
"Once they started seeing the ball there toward the end, they hit it," Bailey said. "After watching the film, I missed a spot to Beltran pretty big. The others hit pretty good pitches. They just got ahold of them."
Bailey was charged with seven runs in five-plus innings and dropped to 3-8 with a 5.52 ERA against the Cardinals, including 0-4 with a 6.93 ERA at Busch Stadium.
Baker pulled Bailey after Pete Kozma's liner struck the pitcher just above his right ankle, with the ball caroming into left field. But Bailey walked off without a limp.
"I was trying to wave him off," Bailey said. "It was more because of giving up the rockets that haven't really landed yet."
The Cardinals advanced only two runners into scoring position in the first four innings and Bailey got two quick outs to start the fifth before running into trouble against the top of the lineup. St. Louis scored 10 runs on 11 hits in the fifth, sixth and seventh off Bailey, Logan Ondrusek and Alfredo Simon.
Jay's second homer just cleared centre fielder Shin-Soo Choo's leaping attempt at the wall. Carpenter followed with a single and Matt Holliday hit an RBI double, prompting a visit from pitching coach Bryan Price.
Beltran then hit his first homer of the season on to make it 4-0.
Adams hit a two-run homer in the sixth off Bailey. Carpenter's two-run shot homer three batters later made it 8-0.
NOTES: Jay has 19 career homers, six of them against the Reds. ... Choo was 0 for 2 with a walk and hit by pitch to end a four-game streak of two hits each game. ... Cincinnati's Todd Frazier was 0 for 11 in the series after opening the season with a six-game RBI streak. ... The RBI was Westbrook's first since hitting a grand slam at Milwaukee on Aug. 31, 2011.