Matz will be available out of the bullpen going forward beginning with Sunday's game against the Mariners, Katie Woo of The Athletic reports.
The left-hander returned from the 60-day injured list as a starter Tuesday in Milwaukee and allowed three runs over 4.2 innings, but he'll be shifted to the bullpen with Lance Lynn (knee) on the cusp of rejoining St. Louis' rotation. Matz has a 6.12 ERA, 1.61 WHIP and 24:12 K:BB across 32.1 innings this season and is now likely to operate as a long reliever.