There's a strong likelihood that Toronto will open the year with an eight-man bullpen, and that limits its overall flexibility for the bench. Two spots will go to a backup catcher and infielder, which leaves only one job up for grabs in the outfield.
"It's going to be tough to go with five outfielders, and we're not sure how the bullpen is going to stack up with how many guys we're going to have down there." Gibbons said. "We've got some questions we've got to answer."
If the Blue Jays do start the year with four outfielders, then it would appear as though Sierra is the early favorite to make the team. He would receive occasional playing time in the outfield and also likely get the start at designated hitter over Adam Lind when a left-hander is on the mound.
Sierra doesn't have favorable splits against lefties throughout the course of his Minor League career, but the hope is that as a right-handed hitter, that will eventually change. Either way, he appears to be the club's preferred option for that role over the left-handed-hitting Gose.
There's also the fact that Sierra can't be sent to the Minor Leagues without being exposed to waivers that will heavily factor into Toronto's final decision.
"He's out of options, so he's got a shot to make the team," Gibbons said of Sierra. "We need someone who can hit lefties. We don't have that guy locked in.
"Over time you become a better hitter; normally the good ones do. He's got a chance to be a good overall hitter, period. But he's not established yet in the big leagues. Hopefully he takes advantage of this and becomes that guy."
The big problem with Sierra potentially making the team over Gose is that it would leave the Blue Jays without a legitimate backup center fielder. Melky Cabrera, Jose Bautista or Sierra could potentially give Colby Rasmus a day off every now and then, but it's a less-than-ideal situation.
If Rasmus were to get injured, then it would likely prompt the Blue Jays to make an immediate roster move by calling someone like Gose up from the Minor Leagues.
Gregor Chisholm is a reporter for MLB.com. Read his blog, North of the Border, and follow him on Twitter @gregorMLB. This story was not subject to the approval of Major League Baseball or its clubs.