Official scorers never give errors on incomplete double plays -- which is really a single play, only retiring the lead runner -- even if the return throw to first is bobbled, bounced, thrown away or just slow-hand late. The only way there's an E is if the batter or another baserunner advances on the miscue.
That's something that never shows up in the box score, but can kill a team if it's habit-forming -- giving opponents extra outs and opportunities to score, and tacking on untold extra pitches onto the arms of moundsmen...
The '04 Red Sox upgraded their defense as much as they could. The '03 club was 4th from the bottom in AL Defensive Efficiency, while the '04s finished 4th from the top. Boston's '03 line-up was monstrous at the plate: eight regulars with 85 or more RBI! So Epstein had the luxury of changing the DP combo of a team that won 101 games (including the postseason); replacing Nomar and Todd Walker -- who could both mash -- with Cabrera and Bellhorn... and it won the World Series.
Both Walker and Bellhorn had some pop, though Walker was a better hitter. He was also a negative dWAR second baseman, while Bellhorn was a positive dWAR...