Glossary of baseball (H)

A tongue-in-cheek expression used to refer to players who had successful careers, but whose stats and/or overall performance are not good enough to put them into consideration for the Hall of Fame. Example of players said to be in the "Hall of Very Good" are Chris Carpenter,Lee Smith, and Mark McGwire.

Said of a team when it scores eight runs in one inning. Broadcaster Eric Nadel used this term on 8 August 2015 when the Texas Rangers sent eight men across home plate in the 11th inning, defeating the Seattle Mariners 11-3. May also be used when a team gets the opposing pitcher charged with eight runs over one inning or a series of innings.

Another source is the fact that early baseball bats usually cracked lengthwise in two pieces. Because of the cost involved, many of these bats were repaired using glue and 2 screws, and the original phrase was " (he)hit it between the screws" subsequently modified since such repaired bats became illegal.

a person who hits a ball with a bat in baseball.

"Unfortunately for his personal power totals, Milledge was bamboozled into believing his liner in the fourth inning against the Chicago Cubs on Thursday night had cleared the left-field fence at PNC Park for his first career grand slam. Dead certain he had gone deep, Milledge raised his fist rounding first base, put his head down and went into a trot. Cool. Double-dog certain because the fireworks guy at PNC set off the pyrotechnics that explode every time a Bucs player goes deep. Music also began to blare. What a glorious moment for the Bucs! . . . Only, the ball had not cleared the fence. It hit the top and stayed in the field of play. As Bucs announcer Bob Walk said, 'Uh oh, uh oh, uh oh, uh oh — we got a problem here.' Milledge was not quite midway between second and third base when he realized the Cubs had him in a rundown. And, yeah, um, he was tagged out. Score that a two-run double and a big ol' base-running blunder."

...
Wikipedia