Historical clue formulations

• Two-bagger: Abbr. — 2018-01-10
• Good baseball hit: Abbr. — 2013-06-20
• Substantial hit: Abbr. — 2010-01-30
• R.B.I. producer, sometimes: Abbr. — 2009-08-13
• Two-bagger: Abbr. — 2006-02-05
• Two-bagger: Abbr. — 1996-09-18