Teams w/ Positive Run Differential
Red Sox +92
Every team on that list is considered to be a serious playoff contender except for the Royals. Several teams that are in the playoff race have a run differential at 0 (Yankees) or below 0 (Nationals). The Royals are the only team under .500 that has a positive run differential, so they are clearly underachieving.
They are 6th in ERA and 23rd in runs, so scoring runs is their major problem. Even there, they've been making improvements.
Runs scored, rank
With the unbalanced schedule, they'll have their chance. They have 11 more games against the Tigers and 8 against the Indians. It is going to be hard for them to compete over the long run with the firepower of the Indians and Tigers.
But, as the Giants have shown in the past few years, a team can get by with a mediocre offense if they can pitch. Their relievers are already dominating (ranked 3rd) and the starters are probably capable of doing more (ranked 15th). They have a big test coming up in the final week before the All-Star Break, with 4 in the Bronx and 3 in Cleveland.