Umpires check pitchers’ hands to make sure they’re not using illegal “sticky” substances that can give the ball extra spin and movement, which would be considered cheating and against MLB rules.

What umpires are looking for

  • Umpires feel the pitcher’s fingers, palms, and sometimes wrists for unusually tacky or sticky spots. Common banned aids include very sticky grip enhancers (like Spider Tack–type products), excessive pine tar, or other homemade mixtures.
  • They can also look at the glove, hat, or belt if something seems suspicious, since pitchers historically have hidden substances there.

Why “sticky stuff” matters

  • Extra‑sticky substances can dramatically increase a pitch’s spin rate, which makes fastballs ride higher and breaking balls snap harder than they normally would.
  • That added movement makes pitches much tougher to hit, so MLB treats it as an unfair advantage similar to using doctored equipment.

When and how often they check

  • Current procedures call for pitchers to be inspected at least once per appearance, usually when they come off the mound between innings or during a pitching change, so the flow of the game is disrupted as little as possible.
  • Starters tend to get checked multiple times in a game, while relievers usually get checked once, though umpires can perform extra checks if they notice suspicious behavior or if the opposing manager specifically requests it.

What happens if they find something

  • If an umpire finds an illegal foreign substance, the pitcher can be ejected on the spot and face an automatic suspension under MLB’s foreign‑substance policy.
  • Teams can also be warned or investigated if there’s a pattern of violations, because the league wants to protect the integrity of the game and show fans that pitching success isn’t coming from hidden tricks.

A little recent context

  • These checks became highly visible and routine starting in the early 2020s, after data showed spin rates jumping and a league‑wide debate erupted about “sticky stuff” and its role in dominant pitching.
  • Even if a pitcher just got shelled, umpires still check them on the way off the field, because the protocols are standardized for everyone and not tied to how well they’re pitching.

Information gathered from public forums or data available on the internet and portrayed here.