Bumgarner and the Giants got worse news Friday.
As MLB.com's Chris Haft writes, Bumgarner has been diagnosed with a Grade 2 sprain of his throwing shoulder, and he's expected to miss at least three months. That would mean Bumgarner wouldn't be in line to return to the rotation until late July -- i.e., well into the second half of the season. As well, that assumes no setbacks during the rehab process.
At present, Bumgarner in his age-27 season has an ERA of 3.00 (136 ERA+) and a K/BB ratio 7/1 after four starts. He came into 2017 with a streak of six straight seasons of at least 200 innings. That's a remarkable run for a pitcher of Bumgarner's relative youth, but it will not be extended this year.
As for the Giants, they're now thin in the rotation for the balance of the first half, barring any trades. That's troubling news for a team that opened play Friday in last place in the NL West and 6 1/2 games behind the first-place Diamondbacks. Long-term, the concern is getting Bumgarner back to full health and back on the Hall of Fame track he has been on.