August was not a good month for Mark Teixeira. He missed another handful of games due to injury problems and hit a grotesquely weak .193/.276/.307 with 2 HR, 9 BB, and 22 K in 98 plate appearances. It was by far his worst single month of this season and the depressing continuation of an even more depressing season-long trend. Teix's production has dropped off in each month as he's dealt with and played through a string of nagging injuries and it appears as though all the wear and tear finally caught up to him in August.
You don't even have to dig too deep to see this. Just check his monthly OPS splits. Teix missed 14 games in April and posted an .862 OPS with a .487 slugging percentage. He missed 3 games in May and posted an .840 with a .472 SLG. Missed 3 games in June and posted a .774 (.471), 8 in July with a .695 (.375), and 5 in August with the aforementioned .582 (.307). The batting average has never been high but it's dropped off significantly over the last 2 months. The BB rate has fluctuated some, but stayed generally consistent from the first half of the season to the second. What's really killed Teix's production and value has been the constant downward slope of his power output.
Looking a level deeper at his August numbers, you'll notice that his strikeout percentage has jumped back up to 22.4%. That's the second worst monthly K rate of the season for Teix and first time since April, when he was super rusty, that he had a K rate over 20%. His 16.7% LD rate is also his worst since April and his 7.1% HR rate is by far his lowest of the year. Teix is still hitting the ball in the air, he just isn't hitting it with the kind of oomph he was in the first 3 months.
Not that we should necessarily be expecting him to at this point. The prevailing thought coming into the season was that Teix's wrist was going to give him problems and most likely hamper his production and at times earlier in the season it was. It's the additional injuries that have crept up that have been the bigger issue. If it wasn't the wrist bothering him, it was the hamstring. If it wasn't the hamstring, it was the back. If it wasn't the back, it was the groin. If it wasn't the groin, it was the lat. if it wasn't the lat, it was the finger. And so on and so forth.
The circumstantial injury evidence combined with the down trending statistical evidence and the weak, slow swings you've seen if you've watched Teix live recently add up to a pretty damning conclusion that Teix is severely worn down and limping to the finish line this season. He's been breaking down for a while now and this season seems like the one in which all the nagging body issues are coming together at the same time to turn Teix into a part-time player to be heading into next season. At this point, the only reasonable thing to hope for is that he can at least hold his body together long enough to finish the season and not suffer any catastrophic injury that could affect him next year.