The Orioles led the AL and ranked third in the majors in Defensive Runs Saved. The Royals ranked fourth in Defensive Runs Saved and led the majors in Web Gems, a number of which you saw in their Division Series sweep of the Angels.
What figure to be the notable defensive storylines of this series?
Caleb Joseph’s impact
Given the difference on defense between Orioles catchers Nick Hundley and Joseph and the Royals' baserunning ability, Buck Showalter seems likely to catch Joseph in each game. Joseph has an advantage over Hundley in both throwing out baserunners and pitch framing.
Opposing basestealers were safe on 62 percent of their tries against Joseph (21 of 55), the third-lowest success rate in the majors (only Christian Vazquez and Yadier Molina were better among catchers with at least 50 games played), but were safe on 86 percent of their attempts against Hundley (31 of 36, seventh-worst in the majors).
Joseph is also very good at pitch framing. He ranked fourth in percentage of called strikes gotten on pitches outside the strike zone (11 percent), trailing only Hank Conger, David Ross and Jose Molina.
Royals catcher Salvador Perez will have an impact on the series as well. The thing to watch for with Perez will be if he can catch a baserunner napping. He tied for the major-league lead among catchers with four pickoffs.
The Royals' fantastic outfield
The Royals' outfield led the majors with 46 Defensive Runs.
The Royals have received excellent outfield defense throughout 2014, particularly from Alex Gordon, Lorenzo Cain and Jarrod Dyson. Gordon and Cain were 1-2 among AL outfielders in Defensive Runs Saved (Gordon also led all outfielders with 13 Web Gems).
Right fielder Norichika Aoki didn't rate well on defense this season, with his primary struggle point being balls hit to the deepest part of the ballpark. It will be interesting to see whether the high right-field wall in Camden Yards gives him any trouble these first two games.
The Orioles' infield is very good
Each of the Orioles four infield positions (as well as all three outfield spots) contributed positive Defensive Runs Saved totals.
The Orioles turned 74 percent of groundballs and bunts hit against their pitchers into outs, the third-highest out rate in the American League. That's significantly better than the Royals, whose out rate was just below 72 percent (71.6)
Of note related to this: The Orioles used a defensive shift on 705 balls in play in 2014, the fourth-most in the majors. The results were good, though not overwhelming (seven Defensive Runs Saved on shifts), perhaps because the Orioles were pretty good even when they didn’t shift.
When the Orioles have a chance to get a double play, they do so at a high rate. The Orioles led the majors in the double play component that gets factored into Defensive Runs Saved (11 Runs Saved). They had the top-ranked second baseman (Jonathan Schoop) and the top-ranked shortstop (J.J. Hardy) in that stat.
Royals shortstop Alcides Escobar tied for the most Web Gems for any player this season (14) and has the most of any player over the last six seasons (61).
Though Escobar excels at the flashy play, it's the easier ones that give him trouble. He's ranked outside the top 10 in Defensive Runs Saved at that position in each of the last three seasons.
To shift or not to shift: Mike Moustakas
The Orioles were among the most active users of defensive shifts in baseball. They'll have a decision to make on what to do when it comes to Royals third baseman Mike Moustakas.
Moustakas is a player against whom defenses regularly shift, and for much of the season, that vexed him. But towards the end of August, Moustakas was finally able to make the necessary adjustments.
Moustakas had nine opposite-field hits in his first 350 at-bats. He had nine in his last 107 regular-season at-bats, plus two more in 14 at-bats this postseason.
Key player off the bench: David Lough
The Orioles have a player who may be extra motivated to beat the Royals: former Royals backup outfielder David Lough.
Lough has 25 Defensive Runs Saved in a little more than 1,200 innings over the last two seasons. He had 10 Runs Saved in right field last season, seven in left field this season. He ranks fifth-best in Runs Saved per 1,000 innings over that span (his former teammate, Cain, ranks third). The Orioles often use him as a defensive replacement in left field.