[mef]

They had this during spring training and it was fantastic. The challenge limit meant it was used rarely, but when it was used it added a fun dramatic element. Players getting to stick it to umpires when they got it wrong, and umpires getting to smirk at players when they got it right.

And at the end of it all, some missed calls get to be corrected.

[cstone]

Agreed - Plenty of hitters have experience with it as well, since it's been around the minors for even longer than this season.

I saw it in practice a few times this year during spring training games, and it was _fast_. Add to that the fact that only pitchers, catchers, and hitters can request one (no managers holding the game up while the replay room checks on it), and it really won't slow the game down at all.

[whycome]

The fun part will be seeing how teams learn to game the system. The batter can call it, but I think it would be hard to stifle any kind of communication from the dugout.

/something higher tech than banging a garbage can obviously.

[carefulfungi]

It will be fun to see if teams prefer batters or catchers use the system. Or if they will coach either side to use it situationally. I think, so far, catchers have better challenge success rates?