Matthes launched a first-inning grand slam to give the Rafters an early lead that they would never relinquish. The top team in the Arizona Fall League's East Division finished the regular season with a 7-3 win over Surprise and will face Peoria in the AFL Championship Game on Saturday.
"It's good to finish strong," the Rockies' No. 20 prospect said. "We've won our last two and it's good to go into the championship feeling good about our performances. Just like anything you always want to get hot at the right time, and we're playing some good ball so hopefully that will carry over to the championship."
The slam was Matthes' fifth homer of the fall and first grand slam since Aug. 2, 2011, when the Alabama alum was playing with the Rockies' Class A Advanced affiliate in Modesto.
The four-run opening inning proved crucial as the Saguaros pitching staff was able to shut down the potent Salt River lineup for much of the afternoon. After the first, the Rafters managed just four singles and one run -- an RBI base hit by Lars Davis in the third -- over the next six frames.
"We saw some good arms all day," Matthes said. "If you look, they outhit us and we probably struck out a dozen or more times, so it was good to get up early. We had some good arms going for us too. I guess for this league it was a relatively low-scoring game."
Surprise pushed a run across in the bottom of the fifth with Texas shortstop prospect Hanser Alberto scoring on a groundout by fellow Ranger Chris McGuiness, and a two-run homer by Whit Merrifield (Royals) cut the deficit to 5-3 two innings later.
That was as close as the Saguaros would get, though, as Nationals' No. 17 prospect Jason Martinson -- pinch-hitting for Washington's top prospect Anthony Rendon in the eighth -- sent the second pitch of his at-bat over the right-field wall for a two-run homer.
Martinson, the Nats' fifth-round pick in the 2010 Draft, came in on a six-game hitting streak but had been unable to find a groove in the AFL, batting just .167 with no home runs entering Thursday.
"Martinson has a lot of pop," Matthes said. "He's shown it in [batting practice] and he's had a lot of balls hard out here in the Fall League without much luck. So for him to give us the four-run lead back was big. He put a really good swing on a ball away and drove it out to right."
Matthes finished the regular season with the team lead in home runs and RBIs (18), and says to bring a championship to Salt River would be a bonus on top of what already has been a very successful fall.
"It's been a great experience," he said. "I've learned a lot. There's been some really competition. I think you'll see a lot of these guys in the big leagues next year as impact players."
Zack Cox is a contributor to MLB.com.mlb This story was not subject to the approval of Major League Baseball or its clubs.