In a sea of injuries this year, one has reigned king.

Before the year started, no one would have guessed that the most destructive of all injuries was the smallest. As I’m sure you’ve figured out by now, we’re going to be talking about the silent killer: the blister.

Throughout the history of baseball, blisters have been a problem for pitchers. The repeated motion of throwing a ball and guiding it with the tips of their fingers, will frequently cause blisters on even the most resilient of hands. Something so small can completely alter a pitchers throwing motion and the movement on their pitches. Despite always being a part of baseball, blisters have occurred at a frustrating rate this year.

This year, Johnny Cueto, Taijuan Walker, Aaron Sanchez, Zack Wheeler and Rich Hill have all been claimed by the blister. Combined, Sanchez and Hill have required five trips to the DL, Walker is yet to come off it, Wheeler just exited his game yesterday (5/27 in Pittsburgh) with one, and Cueto is pitching through his blister to an uncharacteristic 4.64 ERA and 4.22 FIP. The year has just begun and five players have already been affected. How many more will be taken?

Bochy said trainers will check with Cueto in a couple days on blister. Start to start now w/ possibility of pitcher called up. #sfgiants — Henry Schulman (@hankschulman) May 24, 2017

So how can blisters be prevented? Well, it’s not very simple. Blisters are basically unpreventable due to the nature of pitching; it’s just down to whether or not they form and despite popular belief, calluses don’t actually help prevent blisters. They can actually cause blisters to form due to the rough skin pushing against the softer layer underneath.

But can’t the pitcher just slap on some ointment and a band-aid and be back in a few days? Not at all! Blisters can linger for months and if a player comes back too soon, this can seriously aggravate it, extending their time out (think Aaron Sanchez and his 3 trips to the DL or Rich Hill and his blister that has spanned over multiple seasons).

This can push players to extreme lengths. Rich Hill peed on his own hands in an attempt to end his blister problem. Nolan Ryan would actually cut the outer skin off his fingers with a scalpel before each start. Though blisters may often be considered a small injury, they are no laughing matter.

For the rest of the year, we can only keep a positive outlook. Their truly is no reason for all of these blister issues, except bad luck and maybe genetics. Hopefully, we’re just getting them all out of the way before things start to heat up later in the year. However, don’t be surprised if you read another headline reporting a blister related absence.