Marrero, 26, hit safely in 15 of his final 19 games with Pawtucket, batting .370 (23-for-73) with six doubles and three home runs during that span. In 58 games over three stints with Boston this season, the right-handed hitter has batted .212 (32-for-151) with seven doubles, three home runs, and 23 RBI, helping the club to a 27-16 record in his 43 starts. He has posted a .977 fielding percentage (three errors in 130 total chances) at the major league level in 2017 while appearing in 49 games at third base, four at second base, three at shortstop, and one at first base. Originally selected by the Red Sox in the first round of the 2012 June Draft (24th overall), Marrero has hit .208 (45-for-216) with seven doubles, four home runs, and 26 RBI over 96 career major league games, all with Boston (2015-17).
Velázquez, 28, is 2-1 with a 4.08 ERA (8 ER/17.2 IP) in four appearances (two starts) over four stints with Boston this season, allowing zero runs and only three hits in 7.1 innings as a reliever. The right-hander most recently pitched in a major league game on July 18 against Toronto, when he threw 4.0 scoreless innings and earned the win in a 5-4, 15-inning victory over the Blue Jays. He also went 8-4 with a 2.21 ERA (25 ER/102.0 IP) and a .213 opponent batting average in 19 starts with the PawSox, striking out 79 batters and walking 24. A native of Sonora, Mexico, Velázquez made eight scoreless starts of at least 5.0 innings for Pawtucket. The Red Sox purchased his contract from the Piratas de Campeche of the Mexican League on February 18, 2017.