"These guys can swing the bat, and with one swing of the bat, the game can change," Pena said of Orioles hitters, who produced an MLB-leading 211 homers in 2014.
Leiter noted that Orioles center fielder Adam Jones could be a key in the series.
"I know he didn't have a great series [in the ALDS], but I think the element that he brings to the game and he's still a force for opposing pitching coaches and staffs to worry about," Leiter said.
While they were split on who had the starting-pitching edge, with Pena going with the Royals and Leiter going with the Orioles, both agreed that the bullpen edge goes to Kansas City.
"You talk about Greg Holland and the back end [of the Royals bullpen], he just shuts down the door," Pena said. "And I've faced him; I know exactly what it's like to be in the box against him."
Leiter mentioned two other relievers who have come up big for Kansas City.
"Brandon Finnegan, not even a year out of college from TCU, a lefty, got some key outs [in the ALDS]," Leiter said. "I think he's going to be important in this series. … And Wade Davis is the best setup guy in the game."
As for the all-important intangible factors, both Pena and Leiter gave the nod to the Royals.
"The way [the Royals] got into the playoffs, they're riding this momentum that it's just practically unstoppable," Pena said. "Of course, we're taking a break now, which makes a big difference, but these guys have already won; they've already won and they've got nothing to lose and they're coming out just happy to be there."
Leiter pointed to Kansas City's speed as the deciding factor in giving the Royals the intangible edge.
"I think the speed of this team, we saw it so far that this team can beat you with the legs," Leiter said. "Jarrod Dyson, Lorenzo Cain, Alcides Escobar, great defense. … It's going to come down to small-ball … it's going to be an element of good defense and how will they be able to manufacture runs early."