After a rather terrible first half of the season, Mets Opening Day starting pitcher Matt Harvey has been placed on the 15-day disabled list with right shoulder discomfort and will see a doctor to undergo some tests on the injury. The club told reporters (Anthony DiComo) of the news after a 4-2 victory Wednesday.

Needless to say, it has been a disappointing season from an individual standpoint for Harvey. He sits 4-10 for a team that is now 46-38. And take a look at the difference in rate stats from his career marks:

2012-2015: 2.53 ERA, 1.00 WHIP, 9.5 K/9, 7.0 H/9, 2.0 BB/9, 4.78 K/BB
2016 so far: 4.86 ERA, 1.47 WHIP, 7.4 K/9, 10.8 H/9, 2.4 BB/9, 3.04 K/BB

It's a bit mind-boggling to see this kind of a drastic dip in production, but there might be something to it.

Matt Harvey had another rough outing Monday against the Marlins. USATSI

Remember all the discussion about Harvey going past an innings limit that was desired by his camp? He pitched well through it and all the way through the final game of the World Series. Including the regular season and playoffs, Harvey threw 216 innings. Harvey and his agent, Scott Boras, said doctors recommended a 180-inning limit, as this was his first full season returning from Tommy John surgery.

It should be said that Harvey's shoulder is what is injured now and Tommy John surgery involves the elbow. It also should be said that a player pitching through a tired elbow can most certainly do something damaging to his shoulder. We can't connect the dots for certain, but it's possible.

What we do know is that Harvey has lost a a bit over a mile per hour on his fastball from the first half of 2015 and pretty much all of its effectiveness. He has also seen a big dip in effectiveness from his slider (via Fangraphs).

Stamina has also been an issue, because his loses his stuff as the game progresses. Here's what opposing lineups have done.

1st time through order: .236/.287/.343
2nd time through order: .298/.320/.475
3rd time through the order: .419/.474/.593

The league averages:

1st: .246/.310/.384
2nd: .260/.324/.429
3rd: .266/.329/.439

So he goes from above average to below average to holy-cow-he-is-awful. Again, that's a stamina issue that could point to underlying shoulder issues throughout the season.

The Mets still have a very good rotation in Noah Syndergaard, Steven Matz, Jacob deGrom and Bartolo Colon, but they do need a fifth starter until either Zack Wheeler (coming back from Tommy John surgery and Marc Carig reports it'll be over a month) or Harvey are ready to rejoin.

Surely we'll see some more updates in the coming days, but consider this developing for the defending NL champs.