Loewen signed a minor league deal with the Rangers on Monday, Jeff Wilson of the Fort Worth Star-Telegram reports.
Loewen was designated for assignment by the Diamondbacks on Monday.
Loewen's contract was selected from Triple-A Reno on Saturday.
Loewen pitched 0.1 innings Friday, giving up a hit and a walk in Triple-A Reno's 8-6 loss to El Paso.
Loewen was outrighted off the Phillies' 40-man roster Wednesday, Todd Zolecki of MLB.com reports.
Loewen (1-0) got one out in the form of a fifth-inning strikeout to pick up the victory in a 4-3 win over the Mets on Tuesday.
Loewen credits a mechanical alteration with adding 2 mph to his fastball, which now tops out at 95 mph, the Philadelphia Inquirer reports.
Phillies signed OF Adam Loewen to a minor league contract.
Loewen converted from pitcher to outfielder and showed some promise last year in the Blue Jays' minor league system. He was the No. 4 overall pick in 2002.
Blue Jays signed OF Adam Loewen to a minor league contract.
It's not yet clear whether the deal includes an invitation to spring training. Loewen, a pitcher-turned-outfielder, hit just .231/.333/.389 at two different minor league levels for the Mets in 2012. He'll probably wind up serving as organizational depth for the Blue Jays.