This year Todd Frazier has posted a wRC+ 104 -- with rest-of-season projections of 101, 106 and 103 -- at a position where Red Sox third basemen have produced a wRC+ of 61 this year:
http://www.fangraphs.com/statss.aspx?playerid=785&position=3B
http://www.fangraphs.com/leaders.aspx?pos=3b&stats=bat&lg=all&qual=0&type=8&season=2017&month=0&season1=2017&ind=0&team=0,ts&rost=0&age=0&filter=&players=0&sort=16,d
Frazier has an OPS+ of 107 while Red Sox third basemen have an sOPS+ of 63.
https://www.baseball-reference.com/players/f/frazito01.shtml
https://www.baseball-reference.com/teams/split.cgi?t=b&team=BOS&year=2017
Many Red Sox fans underestimate Frazier's worth. ZiPS, Steamer and FanGraphs Depth Charts have only four Red Sox hitters exceeding the rest-of-season WAR projections of Frazier (who is projected to produce at least at the level of Andrew Benintendi).
http://www.fangraphs.com/projections.aspx?pos=all&stats=bat&type=rzips&team=3&lg=all&players=0&sort=24,d