Tillman needed 122 pitches to clear the fifth, and he earned the win in the Orioles' 8-4 victory over the Red Sox.
"You're trying not to use four or five guys out of the 'pen in the first game," Showalter said. "We've got Toronto behind them and they're tough everywhere, especially up there. That was something I was thinking in the dugout.
"Tilly made a big pitch there at the end on (Jackie Bradley Jr.) and he made another one the inning before. It was a challenge for him, but he deserved that. If the guy (A.J. Pierzynski) hadn't had a fister base hit, I probably would have gotten him there, but it's tough to take Tilly out there after that.
"You guys saw. There's not many early in the at-bat outs. J.J. (Hardy) didn't have a ground ball hit to him today. Chris (Davis) and Lombo (Steve Lombardozzi) had one, I believe. If you're going to play against them, you're going to have to battle your way through it. The key was we kept scoring runs when they did, kind of throwing it back.
"Tilly had six days rest. He might have been too strong. I think the credit goes to them more than anything. They have some deep at-bats. It's going to happen. Brian Matusz had four days off and had a background in starting all spring, so we felt like we can extend him, so we'll see what tomorrow brings."
Tillman's ability to limit the damage while laboring is another sign of his maturity.
"I hope so, but it was a lot more Boston than Chris' lack of effectiveness," Showalter said. "You take a look and go through the sheet, the at-bats and pitches seen, it's going to happen. There aren't going to be a lot of early count outs. There's such a fine line between having not enough rest and having too much rest. I've looked at all the numbers on all our starters with six days and five days and four days, skipping a start. We just didn't like his bullpen last time. He actually, I think, was too strong tonight."
Showalter stretched out Zach Britton to three innings and 42 pitches on Wednesday, and Matusz's 2 2/3 innings tonight were the most he's thrown as a reliever.
"I'm thinking that if we get into the season, I'm hoping there won't be as much need for it," Showalter said. "The way their batting order stacks up, I told Brian in the outfield, 'You may have an extended outing tonight.' And he was ready for it. I said, 'It felt like old times, didn't it?' And he said, 'Yes, it did. Don't forget me.'"
Jonathan Schoop had an unforgettable night with a career-high four hits to go with two RBIs.
"As intense as those games are at this level, you do step back and watch Jon," Showalter said. "It's fun to watch. He's got a great look on his face. He's just... real sincere, earnest look. He's not giddy. That's what I like about him.
"He's going to be a good defender whichever infield position he ends up playing. He's just now getting his clock kind of settled in at third base. I think we're seeing some of the results of that."