The chart above from August Fagerstrom of FanGraphs shows which teams this season have had the most and least productive benches.
Fagerstrom summed the WAR of all players following the team's top nine plate appearance leaders in the AL, and the top eight leaders in the NL. The Phillies had the worst bench in baseball with a -2.5 WAR and the Mariners had the second worst bench with a -2.0 WAR. The Dodgers have the most productive bench in baseball with +4.6 WAR and the Athletics come in second with a bench WAR of +3.1.
Fagerstrom concludes the difference between the worst and best benches is worth about six wins this season. Since the price of a WAR is about $6 million on the free market, the difference between having the worst or best bench could theoretically cost a team about $36 million.