The Pittsburgh Pirates acquired right-hander Ron Marinaccio from the San Diego Padres to bolster a beleaguered bullpen, designating Dennis Santana for assignment to clear roster space. Marinaccio has posted a 4.79 ERA over 47 innings this season with 38 strikeouts and 18 walks, and was DFA’d by the Padres before joining the Pirates. Santana, who appeared in 41.2 innings this year with a 6.05 ERA and 37 strikeouts, was designated for assignment and is a free agent at season’s end, with about $1.5 million still owed if claimed. The move places Marinaccio in a likely middle-relief role, replacing Santana as part of a bullpen that now includes a mix of right- and left-handers. Some analysis questions whether the Pirates might have fared better had they kept David Bednar and not traded Santana last year. The team is set to open a weekend series against the Chicago Cubs at PNC Park following the trade.