Historical clue formulations

• Baseball rarities nowadays ... or a phonetic hint to the starts of 17-, 26-, 48- and 57-Across — 2019-04-10
• Once-common baseball events ... and a hint to 16-, 24-, 46- and 57-Across — 2011-04-06
• Baseball fans' delights — 1995-09-29
• Some baseball games — 1994-10-17