DUNEDIN, Fla. -- Spring baseball officially makes its return Saturday afternoon when the Blue Jays open their Grapefruit League season against the Tigers.

Left-hander Ryan Borucki will be on the mound for the opener as Toronto begins to lay the foundation for the season. Vladimir Guerrero Jr. is here, there are multiple jobs up for grabs and a couple of big-name pitchers are trying to get back on track. These are the top five things to watch when games begin in Florida:

The Rule 5

The most intriguing arm in the bullpen belongs to Elvis Luciano. Under normal circumstances, Luciano wouldn't be in Major League camp, but he finds himself with a realistic shot of cracking the roster after being taken in the Rule 5 Draft. Toronto's analytics department is high on the 19-year-old, and the organization would love to find a way to keep him around, but that will be easier said than done for someone who has never pitched above rookie ball. In Luciano's first live batting practice session, he hit Teoscar Hernandez and served up a home run. This might become a disaster, but it's possible the Blue Jays have found a creative way to add a valuable prospect. This spring will provide the answer.

The big arm

Toronto manager Charlie Montoyo knows how good Aaron Sanchez can be, but he wanted to get first-hand experience here in Dunedin. As Sanchez got ready for his first live batting practice, Montoyo stepped into the box for a couple of pitches -- and then quickly retreated.

"Now I know for sure I have no chance to hit anymore," Montoyo joked afterwards. Toronto's first-year manager hasn't been able to stop raving about Sanchez all week. Blue Jays fans can only hope it's a sign of things to come for a pitcher who has as much upside as anyone, but who is coming off a pair of injury-riddled seasons.

• Sanchez impresses in first bullpen session

The big thing to watch this spring will be Sanchez's velocity. The radar gun should tell a pretty clear story as to whether the righty will be able to get back to his 2016 form or whether more issues are ahead.

The phenom

No Blue Jays' list is complete without Vladimir Guerrero Jr. He's the best prospect in baseball, and this will be the first time he steps into the box against Major League pitching.

While Guerrero will continue to steal the spotlight, he's not the only big-name prospect in camp. Bo Bichette, Cavan Biggio and Danny Jansen are here, too -- in total, 18 of the Blue Jays' Top 30 prospects as ranked by MLB Pipeline are with the team. A couple more under-the-radar names to keep an eye on this spring are right-handers Yennsy Diaz and Patrick Murphy, who were added to the 40-man roster this offseason to avoid exposing them in the Rule 5 Draft.

The battle in left

The writing appears to be on the wall for Dalton Pompey, who should be considered a long shot to crack the roster. Pompey is out of options and faces the possibility of leaving the organization at the end of camp. Hernandez and Billy McKinney are expected to platoon in left field, which would eliminate any possibility of Pompey making the team. Pompey could put some pressure on the organization with a good spring, but his odds are not good and he likely needs an injury or two to stick around.

Where will they play?

Devon Travis in left field? It's going to happen this spring, and he won't be the only player trying to learn a new position. The Blue Jays are emphasizing versatility and Montoyo intends to move his guys around to make sure they get enough at-bats. Lourdes Gurriel Jr., Brandon Drury and Richard Urena are some of the other infielders who are going to move all over the field. Not all of these positions will be realistic in the regular season, but these games will prove what's possible -- one way or the other.