Adam Kilgore of the Washington Post interviewed Nationals pitching coach Steve McCatty about a variety of topics today, including the idea that Edwin Jackson has been tipping his pitches for years now.
McCatty reviewed video of Jackson’s starts and thinks he was letting batters know what was coming out of the windup:
These guys are so good, they look at every single thing. Hitting coaches are looking at every guy on video. You pick up on stuff. It’s simple as not laying your hands down on a slider or fastball or changeup. Once these guys see it, it makes a big difference.
Most pitchers are better working from the windup with no runners on base, but the opposite has been true for Jackson during the past three seasons. Kilgore notes that he held opponents to a .246 batting average and .693 OPS out of the stretch, compared to a .283 batting average and .782 OPS out of the windup.
Whether or not that actually means he was tipping pitches on a regular basis and is capable of significant improvement if McCatty helps him fix that is obviously unclear, but it at least provides some reason to think Jackson has more upside than he’s shown.