PITTSBURGH -- Left-hander Kevin Siegrist is on the suspended list at Triple-A Indianapolis after failing to report, the Pirates announced on Friday.

On Thursday, the Bucs said that Siegrist had refused his Minor League assignment and thus became a free agent. On Friday morning, the club issued a clarification. There was a clause in Siegrist's Minor League contract that stated he would accept a Minor League assignment if he was not offered a Major League opportunity by the Pirates or any other club.

Pittsburgh did not place Siegrist on its Opening Day roster and did not call him up before the start of Triple-A Indianapolis' season on Friday. But Siegrist chose not to report to Indianapolis, so he was placed on Indianapolis' suspended list.

Presumably, the Pirates would like to keep Siegrist in their organization if possible. All three left-handed pitchers on their 40-man roster -- Steven Brault , Felipe Rivero and Josh Smoker -- are on their active roster. Aside from the suspended Siegrist, there are no lefties on Indianapolis' season-opening roster.

Siegrist, 28, owns a 3.04 ERA and 1.22 WHIP in 276 career appearances. He was one of the Majors' most reliable relievers in 2015-16, posting a 2.44 ERA with 156 strikeouts in 136 1/3 innings. He struggled last year, however, recording a 4.81 ERA and 1.55 WHIP in 39 1/3 innings over 46 appearances.

Toward the end of Spring Training, the Pirates expressed some concerns about Siegrist's velocity. They believed he would benefit from time in Triple-A to build up arm strength before being considered for a callup to join their bullpen. When the Bucs signed Siegrist to a Minor League deal on Feb. 24, they hoped he would emerge as a late-inning option for their young, inexperienced relief corps.

"We don't want this to be just about velocity, but he's had more velocity when he's had his better seasons," general manager Neal Huntington said on March 26, when the Pirates reassigned him to Minor League camp. "There has been a trend downward in the average velocity and that has continued this spring. ... Our thought in this process is to let him continue to build arm strength and get back to [being] that guy who was effective in 2016 and before that."

Around the horn

• Indianapolis' Opening Day lineup included top prospects Kevin Newman at shortstop, Kevin Kramer at second base and Austin Meadows in center field. Jose Osuna , one of the last position players cut from Spring Training, started at third base.

Jordan Luplow got the nod in right field with Max Moroff serving as the designated hitter, Jacob Stallings behind the plate, Erich Weiss at first base and Chris Bostick in left field. Right-hander Nick Kingham , Pittsburgh's No. 13 prospect, started the Triple-A opener.

• Manager Clint Hurdle said the Pirates will continue to trust their middle-relief trio of Dovydas Neverauskas , Edgar Santana and Smoker. The Bucs believe all three will grow into their roles, with Hurdle pointing to Santana's improvement in the sixth inning of Thursday's 5-2 victory over the Reds as a sign of progress.

"Neverauskas, it's been a mixed bag. Santana, it's been a mixed bag. Smoker, it's been a mixed bag," Hurdle said. "We still need to find out what [Smoker] can do. … There needs to be a settling-in period, and I think we saw some of that last night with Santana. I believe we'll see it with Neverauskas."

Adam Berry has covered the Pirates for MLB.com since 2015. Follow him on Twitter and Facebook and read his blog.