"You want to make sure he's fully comfortable and his pitches have both quality and comfort for him," Hinch said. "It could happen quickly. It could also be a couple of more outings. We're trying not to make any judgments until we continue to get more information and evaluating that versus what we're doing here."
Of course, the Astros' bullpen has been pitching well without Fields. Right-hander Will Harris, who made the club because Fields began the year on the disabled list, has made 19 consecutive scoreless appearances dating to last season, including consecutive two-inning outings Saturday and Sunday in Arlington.
With Luke Gregerson, Pat Neshek, Chad Qualls, Tony Sipp and Joe Thatcher entrenched in the bullpen, the Astros would have to make a move with Harris or long reliever Samuel Deduno, who's done a nice job as well.
"Will Harris has been one of our best relievers," Hinch said. "He's taken the ball in a couple of different situations, including the back-to-back two-inning games. He's done very well in his opportunity and we like what he's doing."
Fields established himself as a key weapon in the bullpen after posting a 4.45 ERA in 54 2/3 innings last year, leading the relievers in strikeouts (70), innings and strikeouts per nine innings (11.52).
"We want to be extra careful with him," Hinch said.
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.