Zack Greinke pitched through the flu on opening day

Zack Greinke's poor opening day start came as a shock to many. After not giving up six runs in a single game all last season, the 32-year-old Arizona Diamondbacks pitcher gave up six runs in a single inning Monday. Greinke, who threw at least six innings in every start last year, was pulled after just four in his debut with the D-Backs. He allowed a total of seven runs.

For all of those reasons, it was an uncharacteristic start for the usually dominant Greinke. While some will want to blame expectations or opening day jitters, it appears another factor may have played a big role in Greinke's struggles.

	Ken Rosenthal @Ken_Rosenthal
Sources: #Dbacks’ Greinke pitched with flu. Did not come close to missing start; decision that he would pitch was made day before. 8:54 AM - 5 Apr 2016

According to Ken Rosenthal of Fox Sports, Greinke was feeling under the weather before his start. Though, as Rosenthal notes, the club never seriously considered moving Greinke out of his spot. He was deemed healthy enough to pitch on opening day the night prior to his start.

If true, that probably explains his poor stat line. San Francisco Giants ace Madison Bumgarner also pitched through the flu during his opening day start, and he didn't look like his usual self either. Bumgarner was tagged for three runs over five innings, and gave up a surprising five walks during the performance. Having the flu is serious business if you're a pitcher.

At the same time, there's no benefit for this news coming out now. Even if it's true, it looks like someone is making an excuse for Greinke. Would we have known about his illness had he gone out and dominated the Colorado Rockies in his first start, or did this leak because Greinke struggled?

It probably won't matter in a few days. All Greinke needs to do is go out and perform in his next start, and people will forget about his opening day flop. Until then, though, his performance will be picked apart. While Greinke can, and has, dealt with that type of thing before, it's unclear whether manager Chip Hale will be able to handle the increased scrutiny that comes with heightened expectations.