The Los Angeles Dodgers were floundering before outfielder Yasiel Puig arrived. Jose Iglesias helped the Detroit Tigers move forward when their starting shortstop was suspended.
The Atlanta Braves? They owe part of their success to Evan Gattis and Julio Teheran, two players in their first full seasons in the major leagues.
There are now eight teams remaining in baseball's post-season, and almost all of them have at least one key rookie who will soon be on the spot. These players have earned the confidence of their managers, but that doesn't mean there won't be growing pains along the way, now that the stakes are higher.
"Everybody, whether you've played 100 years or you're a rookie, there's always a little anxiety when you get to post-season play. It's like teams playing in the Super Bowl," Detroit manager Jim Leyland said. "I don't care how long they've played, there's a difference. It's good to be a little nervous, but it's bad to be scared. They're two different things. It's a great experience, and for rookies, everybody's got to go through it at some point."
The American League playoffs opened Wednesday night with a rookie on the mound, when Cleveland's Danny Salazar struck out three of the first four hitters he faced. The Indians lost 4-0 to Tampa Bay, meaning Rays outfielder Wil Myers will have a chance to play on. He hit .293 in 88 games this year, making a push for the AL Rookie of the Year award.
There are rookie pitchers, such as Teheran, Gerrit Cole of Pittsburgh, Shelby Miller of St. Louis and Sonny Gray of Oakland. And the hitters aren't bad, either. Gattis and Iglesias have been impressive all year, and Puig's first few weeks with the Dodgers were spectacular, helping Los Angeles overcome a poor start to the season.
"He's been a real key for this club, just from the energy level and the clutch hits he's been getting and the fun he has in the clubhouse," Los Angeles outfielder Carl Crawford said. "So he's definitely a guy that gets the team going every day, and we all feed off of that."
Puig hit .319 with 19 home runs in 104 games, but at times, his aggressiveness led to mistakes like overthrowing cutoff men, getting thrown out going for an extra base or getting picked off after taking too big a lead at first base.
"He's definitely going to have to watch that," Crawford said. "Baserunners are at a premium in the playoffs, so you don't want to get picked off in a situation where you can't afford to."
The last rookie to win a World Series or championship series MVP award was right-hander Livan Hernandez, who won both for Florida in 1997. The only other rookie to win a World Series MVP was Larry Sherry of the Dodgers in 1959, according to STATS.
Will any of this year's young standouts have that type of impact? Iglesias was an unexpected addition to Detroit's roster shortly before the trade deadline. The Tigers acquired him from Boston — another eventual playoff team — because Jhonny Peralta was on the verge of being suspended as part of baseball's drug investigation. Peralta is back and part of the post-season roster, but he'll likely play in the outfield. The smooth-fielding Iglesias is Detroit's everyday shortstop now.
The Tigers face Oakland in the division series. In Game 2 on Saturday night, the Athletics will send the 23-year-old Gray to the mound. He made his debut in July and went 5-3 with a 2.67 ERA.
"It's been so much fun and I feel like I've learned so much since I've been here," Gray said. "It's fun to win, to come here and win."
The A's also plan to start rookie Dan Straily in Game 4, if necessary.
Cole, the No. 1 pick in the draft in 2011, went 10-7 with a 3.22 ERA this season. He'll start Game 2 of the division series against St. Louis. The Cardinals had a couple impressive rookies in their rotation this year in Miller and Michael Wacha, although it's not yet clear if they'll start during this series. Rookie first baseman Matt Adams will surely be in the mix after hitting 17 homers for St. Louis.
Miller, who went 15-9, already feels he's come a long way since the beginning of the year.
"It used to be throw the fastball, see if they could hit it. That would run my pitch count up a lot," Miller said. "Efficiency has been a big thing for me lately and I'm just trying to get deeper in games and help the bullpen, be more of a starting pitcher, do a better job of getting hitters out quicker. There's still room for me to improve."
Teheran had a similar season to Miller, going 14-8, and he's one of a couple rookies who could be crucial for the Braves when they take on Puig and the Dodgers. Gattis hit 21 homers and drove in 65 runs while playing mostly catcher and left field.
His approach to the post-season?
Don't try to do too much.
"I want to play solid defence. I want to hit for a better average and I want to put up good at-bats every time," Gattis said. "I don't want to be an easy out or an easy double play or anything like that. I want to hit the ball hard in every at-bat."
AP Sports Writers Tim Booth R.B. Fallstrom, Charles Odum and Steven Wine contributed to this report.