Here are A.J. Pollock's 2015 counting stats and Xander Bogaerts' 2016 stats prorated for the entire season:
AJP .315/367/.498/.865, 132 OPS+, 111 R, 20 HR, 76 RBI, 39 SB
XB .329./.388/.475/.863, 126 OPS+, 121 R, 18 HR, 104 RBI, 20 SB
I suspect the runs and RBI totals are impacted by a 2016 Red Sox lineup that is probably more productive than the 2015 Diamondback lineup.
Learn more on the arbitration process:
http://bizofbaseball.com/index.php?option=com_content&view=article&id=643:arbitration&catid=44:business-of-baseball-glossary&Itemid=75
http://www.sportingnews.com/mlb/news/mlb-salary-arbitration-process-breakdown-spring-training-2016/4jkawqkczi8i17cb4rhqjxseh