At this point in the season last year, the Chicago Cubs defense was leading all other teams in DRS. They were able to hold onto that lead, topping all other defenses by saving 107 runs by the end of the 2016 season. This season, however, the Cubs have not been as dominant, as their seven runs saved with their defense does not even crack the top six best defensive teams. With notable losses such as Dexter Fowler and David Ross this offseason, the Cubs have some additional adjustments to make if they look to regain the defensive prowess that they had last season. By costing their team six runs, the Cubs outfield is tied for fourth worst so far this season. With right fielder Ben Zobrist, center fielder Jon Jay and left fielder Kyle Schwarber (third worst DRS of any player, costing five runs) among the ten worst at their positions, the Cubs have some necessary modifications to make in the outfield.
The Houston Astros, who have been among the top two best defensive teams at the conclusion of each season for the past two seasons (2015-2016), are another team who just missed making the top six best defensive teams at this point in the season. As opposed to the Cubs, the Astros' issues aren't due to making adjustments as a result of their losses from the offseason. Instead, their returning players are the defenders who are struggling, particularly their infielders who have cost their team a league-worst nine runs. Some of the negative contributors to that total are shortstop Carlos Correa (-2 Runs Saved), third baseman Alex Bregman (-2 Runs Saved), first baseman Yulieski Gurriel (-2 Runs Saved) and second baseman Jose Altuve (-1 Runs Saved).
Another team who sees themselves in a defensive hole is the Arizona Diamondbacks, who only two seasons ago in 2015 led the league in DRS by saving 72 runs. However, it is a different story for their defense so far this season as they have the league's second worst DRS by costing nine runs. They've struggled with both outfield and infield play, ranking fourth worst in outfield DRS by costing six runs and ranking tied for sixth worst in infield DRS by costing three runs.
Again, a team's defensive performance in this smaller sample size of games does not make or break their season. Throughout the remainder of the season, it will be interesting to keep up with teams like the Cubs, Astros and Diamondbacks to see if they successfully make their adjustments and find themselves back at the top of team defense.