They should make all goalkeepers play baseball/softball and take grounders.......OK, I feel better now!
Not just GKs. Our older kid (forward) played travel ball until he committed to soccer only, and I can tell you that his baseball training still helps today on the soccer field.
Baseball teaches the players to judge fly balls (i.e., know where soccer ball in the air falls, including reading the spin), how the player backs up first, then move forward to the ball; hence dragging the defender back further than needs to be and moving forward to create space to settle the in the air ball as it comes down or one-touch pass to a teammate. Also know what angle to take for attack and defending a play versus the ball as well as free space.
Those that never played baseball at a competitive level just don't know all intricacy of baseball and how it can helps soccer.