SEATTLE -- Mariners general manager Jerry Dipoto says Wednesday's swap of Mike Montgomery to the Cubs isn't a sign of selling this year as the non-waiver Trade Deadline approaches, but rather getting the best deal for a hot player in order to help his franchise for this season and beyond with the addition of Minor League prospects Dan Vogelbach and Paul Blackburn.
Seattle also sent Triple-A starter Jordan Pries to the Cubs in the four-player deal.
"The attraction here was getting younger and deeper and really starting to fill some positions of critical needs for us moving forward," Dipoto said after Wednesday's 6-5 walk-off win over the White Sox.
The Mariners see Vogelbach as a Major League-ready hitter with a big upside, while Blackburn is a former first-round compensation pick who could challenge for a rotation spot as soon as next year. Vogelbach will report to Triple-A Tacoma, but Dipoto indicated he's not far from joining the big-league club.
"I feel the left-hand offense that Dan Vogelbach brings at some point in 2016, and for years beyond, was too appealing to pass up," Dipoto said. "He has a chance to have a real impact in the middle of an order. He rakes everywhere he's been."
Dipoto felt he was dealing from a position of strength in moving Montgomery, who has been a huge surprise this year while going 3-4 with a 2.34 ERA in 32 games, including two starts after moving into the rotation just before the All-Star break.
But with Félix Hernández returning on Wednesday and Taijuan Walker expected to come off the disabled list in early August, the Mariners have rotation depth and also have lefty Vidal Nuño filling a similar versatile role in the bullpen.

"Some time in the next two weeks, Taijuan Walker effectively replaces Mike Montgomery," Dipoto said. "I don't know that that's a downgrade for us. Mike did a great job and Taijuan obviously is Taijuan. He has tremendous stuff and upside and he'll re-enter our rotation. We feel we're still seven deep in terms of guys that can start a game today."
The Mariners had scheduled Montgomery to start again Sunday in Toronto, but can slide Wade Miley back into that role on normal rest and also have Wade LeBlanc now available in either a starting or long relief role after regaining Hernandez and having three off-days before Walker's expected return.
Montgomery said he had mixed emotions after learning about the deal in the eighth inning of Wednesday's game.
"I was a little sad at first, realizing I'm not going to be here with these guys in this city," Montgomery said. "But at the same time, I'm excited going to a good team and I'm ready to go contribute any way I can and help them win a World Series."

Vogelbach, 23, the 20th-ranked prospect in the Cubs' system according to MLBPipeline.com, had a .318/.425/.548 line in 89 games at Triple-A Iowa with 16 home runs, 18 doubles and 64 RBIs. He was a second-round Draft pick in 2011 and Dipoto says he's greatly improved his first-base defense this past year.
Blackburn, 22, was a first-round selection in 2012 (56th overall), and was 6-4 with a 3.17 ERA in 18 starts at Double-A Tennessee. Dipoto says he'll report to Double-A Jackson.
"He's methodically moved through every level with the same performance," Dipoto said. "He has a high ground ball rate, throws strikes and is a comp first round pick that we feel projects as a No. 4 starter in the big leagues with three pitches."