The Pittsburgh Pirates suffered their seventh loss in their past 10 games Tuesday night, this one an 8-4 loss at home to the Washington Nationals (box score). The Pirates are 16-23 and sitting in last place in the NL Central. It has not been a good start for them. Not at all.

Franchise player Andrew McCutchen went 0 for 4 with a strikeout against the Nationals, and while every player has 0 for 4s throughout the season, they've become all too common for McCutchen. Tuesday's game dropped his season batting line to .206/.280/.390 in 157 plate appearances. By weighted runs created, McCutchen has been 22 percent worse than league average offensively.

McCutchen, who turned 30 in October, suffered through a down season in 2016, at least relative to his standards. He hit .313/.404/.523 (157 OPS+) from 2012-15, MVP caliber numbers. Last season McCutchen slipped to .256/.336/.430 (103 OPS+), which is essentially league average. This year he has fallen even further. The trend is hard to ignore:

It's true McCutchen had a strong finish to 2016, and he might very well do the same thing in 2017, but it is worth noting he got off to a much better start last year. This year's .206/.280/.390 batting line comes in 37 games. Through 37 games in 2016, McCutchen was hitting .255/.345/.484. He was 22 percent better than the league average hitter. This year he is 22 percent worse.

Why, exactly, is McCutchen struggling? Good luck finding the answer to that. The Pirates and McCutchen are trying to figure it out themselves. The symptoms are clear. McCutchen's hard contact rate is way down and his ground ball rate is way up. From FanGraphs:

Andrew McCutchen is hitting more ground balls and making more weak contact. FanGraphs

Putting the ball on the ground weakly is a great way to drag down offensive numbers. The question is why is McCutchen struggling to hit the ball in the air with authority? If you're the Pirates, you almost have to hope he's playing through a minor injury, because at least then you would have an explanation. Perhaps it's a swing mechanics issue. McCutchen could be fighting some timing problems. That would be a good explanation too. At least that would be fixable, in theory.

What the Pirates don't want to be true is McCutchen losing bat speed. There's no real way to fix that. He could start his swing earlier or switch to a lighter bat, but generally speaking, once a player begins losing bat speed, he continues to lose it. He doesn't get it back. It might seen unprecedented for a player of McCutchen's ability to lose bat speed at 30, in what should still be the prime of his career, but it has happened before. It happened with Andruw Jones. Jones hit 41 home runs at age 29 and was done as an everyday player by age 31.

Is Andrew McCutchen following the Andruw Jones career path? USATSI

It is worth mentioning that among the 188 players with enough plate appearances to qualify for the batting title, McCutchen ranks 178th with a .215 batting average on balls in play. His career BABIP is .328, which suggests he's due for an uptick. Then again, if he has lost bat speed, it wouldn't be correct to assume he'll revert to his career BABIP. He's a different player now. Again, weakly hit grounders don't often go for hits, and that's what McCutchen is hitting a lot of right now.

The Pirates spent most of the offseason shopping McCutchen in trades, and on a few occasions, it seemed like a deal was imminent. Nothing came together and McCutchen remains with the Pirates. He's off to the worst start of his career, further dragging down his trade value. And if he keeps this up, exercising his $14.5 million club option for 2018 will suddenly become a very difficult decision for the last-place Pirates.