Mark Teixeira had a rough Spring Training, earning just 3 hits in 45 plate appearances in his recovery from wrist surgery. According to Michael Kay, at some point late in March, Kevin Long noticed that Teixeira accidentally changed something in his batting mechanics to protect his wrist. Whatever they noticed and corrected seemed to work immediately, as the first baseman earned 2 base hits in his first game of the season, and barely missed a home run in his first at bat. Teixeira will be an ongoing storyline this season. The switch hitter tends to struggle in April, and this will probably be his most challenging month ever considering the seriousness of the surgery he's recovering from. Teixeira already admitted to the media that his wrist will never be the same again, and that he'll never be able to treat it like he had in the past. He later clarified that it's maintenance that will have to increase in keeping the wrist healthy, and he doesn't expect a dip in his offensive production. Still, I was curious to see what Long and Teixeira corrected in his swing, as it could easily be something that shows up in future at bats.
The GIF above shows Teixeira making hard contact from a March 13th game against the Phillies, and his first at bat of the season against the Astros on April 1st. His set up, stride, and stance look the same. It's not until Teixeira prepares for contact that you'll see a change.
Initially, when I made this GIF, I thought I'd made the mistake of messing up the timing between each video. The points of contact look off, but they're actually dead on. Teixeira has gained a tremendous amount of bat speed over the last few weeks, which is obviously a positive sign. The correction that Long and Teixeira made seems to be in his hands and wrists.
This is the frame before Teixeira makes contact with both pitches. Keep in mind that both pitches are in different locations, but in the end they're not terribly far off on the x-axis. From simply watching the GIF above, it looks like Teixeira's swing gets long in Spring Training, and that he's going out across the plate to hit a ball away. Yes, that pitch is down in the strike zone compared to the other at bat, but it also catches plenty of the plate.
In Spring Training, Teixeira had a bad habit of making weak contact, and this was due to the problem we see in the GIF above. Teixeira extends his hands and his bat on contact, which forces him to stay back on pitches and hit the ball off the end of the bat. It's easy to see why he'd subconsciously do this, as it takes less stress of his wrists and exposes his arms in the strike zone for a much shorter period of time.
In the video from April, Teixeira keeps his arms inside the pitch, which allows him to transfer power more efficiently. As I mentioned above, this puts more stress on his wrists and it also exposes the wrists to possible inside pitches.
In Teixeira's third at bat of the game, he made contact with two more pitches further away in the strike zone. Even with the pitches further away in the zone, Teixeira still stays back and keeps his arms in the proper position. In all of these corrected instances, he seems to keep his left arm much more bent than we saw in Spring Training, and the elbow on his right arm bent towards the pitcher, as opposed to nearly fully extended.