With less than 70 Major League innings between the two of them, Jarred Cosart and Taijuan Walker have just gotten a taste of the Major Leagues.
They'll face each other as the Astros and Mariners begin a three-game series on Monday.
It's the last chance for the Mariners to get a look at Walker, MLB.com's fourth-ranked prospect, before he's shut down for the season to contain his innings. The 21-year-old has impressed with his power fastball that helped him fan 160 batters in 141 1/3 innings between Double-A and Triple-A this season. And he's allowed just four earned runs in 10 innings over two Major League starts, lasting five innings each time. He held the Astros scoreless in his first career start on Aug. 30.
"He's electric," said Astros right fielder L.J. Hoes. "A 98-mph fastball, a 92-93-mph cutter, it's tough. It says he's throwing 96, but it seems way harder than that because he's so big. When you've got somebody that big, with that stature, throwing that hard, you've got to battle him and hopefully get a couple of hits."
The Mariners have been slowly and steadily letting Walker pitch more and more innings each year. After throwing 96 2/3 innings in Class A as an 18-year-old in 2011, Walker threw 126 2/3 innings in Double-A in '12 and has 151 1/3 combined innings between Triple-A Tacoma and the Mariners in 2013.
"Just treat it as any other start; I'm going to go out there and compete and give my team a chance to win," said Walker, who is making his first start at Safeco Field. "It's been great. The team's been very welcoming. Of course they haze you a little bit, but other than that it's been fun, had a good time.
"It would feel good to end the season on a good note. But if i don't, it is what it is, just go into the offseason and work hard and get ready for next year."
Cosart, 23, impressed in Triple-A, striking out 93 batters in 93 innings before making a seamless transition into the Astros' rotation. While the strikeout numbers have yet to transfer over, Cosart has posted a 2.13 ERA over nine starts, allowing just three homers. He's allowed just eight homers in 148 innings between Triple-A and the Majors this season.
Cosart, who came over in the trade that sent Hunter Pence to the Phillies at the 2011 Trade Deadline, had his first rough outing of his young career last time out against the Twins last Tuesday, when he pitched just four innings, allowing four runs, including two homers.
"Whenever your pitch count's spiked that high, that fast, it's just a lot of deep counts and he just did not have a lot of fastball command," manger Bo Porter said. "He wasn't able to get to his put away breaking stuff because he wasn't commanding his fastball."
The Astros lost the last three in a frustrating four-game series against the A's in which Porter was ejected twice. But the young rotation has been a bright spot: The four rookies, Cosart, Brad Peacock, Brett Oberholtzer and Paul Clemens, have a combined 2.55 ERA in 24 combined starts since July 12.
Astros: Minor affairs
The youngest team in the Majors with an average age of 25.9 years, the Astros recalled four players from Triple-A Oklahoma City over the weekend.
Right-handers Rhiner Cruz and David Martinez, infielder Brandon Laird and utility man Jimmy Paredes were in uniform on Sunday.
While the Astros have seen 14 players make their Major League debuts this season and are currently carrying 17 rookies on their roster, the young organization has hope for the future -- it became the first club since 2003 to have six Minor League teams qualify for the postseason.
Mariners: Wilhelmsen makes positive return
Tom Wilhelmsen started the year as the Mariners' closer, lost the job, was sent to the Minors -- where he struggled over 12 innings, allowing 14 runs -- and was recalled to the big league club when rosters expanded on Sept. 1.
So far, so good. Wilhelmsen hasn't allowed a run in three outings spanning 1 2/3 innings.
"Where he was at the end vs. where he was at the beginning, were night and day for me," manager Eric Wedge said. "This guy obviously has to get his confidence back, he has to trust his fastball, trust his stuff. He has to get back to the bulldog mentality. And he has to do it.
"He took the job as the closer and he lost the job as closer. That was something that he did. So what he has to do is get himself back to being a guy who is a viable option for us up here at this level. There's no reason he shouldn't do that. But it has to start up here," Wedge said, pointing to his head. "He's only pitched a few times. It takes time."
• The Astros are 34-34 when they score at least four runs. They're 13-61 when they score three or fewer.
• Felix Hernandez will throw a bullpen session Monday to test his back before his scheduled start Wednesday.