CHICAGO -- It's a good thing that they have large meeting rooms at the Cubs' complex in Arizona.

When their pitchers gather for the first meeting of Spring Training, there will be almost enough of them assembled to fill a 40-man roster. And that's despite the fact that the Major League staff currently has zero vacancies.

Thirteen pitchers -- nine holdovers from the World Series and newcomers Wade Davis , Brett Anderson , Koji Uehara and Brian Duensing -- are in line for introductions at Wrigley Field on April 10, when the Cubs once again celebrate their victory in Game 7 last November. Yet they are set to have 39 pitchers in camp.

Yes, 39. Catchers will be busy.

Jonathan Lester , Kyle Hendricks , Jacob Arrieta , John Lackey , Mike Montgomery, C.J. Edwards , Hector Rondon , Justin Grimm , Pedro Strop , Anderson, Davis, Uehara and Duensing are known quantities. Anderson and Duensing must show they're healthy and on track but in general these guys have the luxury to pace themselves toward April.

But that hardly means camp will be dull, as there are lots of intriguing storylines lower on the depth chart. Here's a clip-and-save breakdown of those guys, by their purpose in camp:

Rule 5 guy

Caleb Smith , a live-armed lefty from the Giants' organization, has struck out 13 per nine innings but never pitched above Class A. The Cubs don't seem to have any place to put him, but they liked him enough to pay the Brewers to select him for them in the draft of unprotected Minor Leaguers. Since Smith can't be sent out without being offered back to San Francisco, he'll be in a one-of-a-kind situation in camp.

First responders

RHP:Jim Henderson, Fernando Rodriguez , Felix Pena , Williams Perez , Jake Buchanan and Seth Frankoff.

LHP:Jack Leathersich and David Rollins .

Henderson and Rodriguez might be the most important depth guys in the group of pitchers going to camp without jobs. Henderson saved 28 games for Milwaukee in 2013 and is healthy again after a battle with shoulder injuries that limited him in '14 and '15. Rodriguez made 90 appearances for Oakland the past two seasons. His four-seam fastball averages 94 mph with deception and life, giving right-handed hitters fits.

Pena, a holdover from the Jim Hendry regime, made his Major League debut last season. He flashed the same ability to use his fastball-slider combination to get strikeouts that he had shown the past two seasons in Double-A and Triple-A. Pena is capable of throwing multiple innings.

Perez, signed recently to a Minor League contract, was dropped by the Braves after making a combined 31 starts the past two campaigns. He'll enter his age-26 season most likely working alongside Buchanan and Frankoff in the Triple-A rotation. Buchanan won a start for the Cubs in September, throwing five scoreless innings in Cincinnati. Frankoff did a nice job this winter as a starter in Venezuela.

Leathersich is a lefty with upside who could step in when there's a need. The Cubs like him enough that they claimed him on waivers from the Mets in 2015 while he was recovering from Tommy John surgery.

Rollins, who made 31 appearances with Seattle the past two seasons, is this year's Where's Waldo? guy. He was the object of five waiver claims this offseason -- from the Mariners to the Cubs, the Cubs to the Rangers, the Rangers to the Phillies, the Phillies to the Rangers and finally back from the Rangers to the Cubs. So Rollins is in demand, anyway.

Next wave

RHP:Eddie Butler, Jose Rosario , Duane Underwood Jr. and Pierce Johnson .

LHP: Rob Zastryzny .

Zastryzny is the first pitcher drafted by Theo Epstein's Chicago regime to reach Wrigley Field, and he looked comfortable in a Major League uniform. He's more about pitchability than stuff and a fast start at Iowa could make him a candidate for a midseason promotion.

No one in camp is more interesting than Butler, who qualifies as the 7A starter after being acquired from Colorado in a minor trade earlier this week. He was the 46th overall pick of the 2012 Draft and was a highly regarded prospect with the Rockies, but he couldn't crack the combination to the safe at Coors Field.

You hear about pitchers who are better after Tommy John surgery, and Rosario looks like one of them. He missed 2015 while recovering from surgery and turned in a terrific performance last season, when he was used exclusively in relief.

Underwood, 22, should return to the Double-A rotation this season, which isn't really behind schedule. But the hype about him isn't what you'd expect for a second-round Draft choice. Johnson was the second player drafted by Epstein in Chicago, after Albert Almora Jr., and carried big expectations coming out of pitching-rich Missouri State. He's had a hard time staying healthy and pitching effectively and is entering a make-or-break spring and season.

Medically cleared

RHP: Conor Mullee , Ryan Williams, Aaron Brooks and Andury Acevedo .

LHP: Zachary Rosscup and Manny Parra.

Rosscup was acquired in the Hendry trade that cost the Cubs future Rays ace Chris Archer. Rosscup made 61 appearances for the Cubs in 2013-15. He's coming back from arthroscopic surgery on his shoulder last May and intent on working his way back into a role as a late-inning neutralizer of left-handed hitters.

Williams, a product of East Carolina University, has pitched more effectively than anyone else in the Cubs' system since being drafted in the 10th round in 2014. His 2.29 career ERA includes his work at Iowa last season, before shoulder tightness stopped him after nine starts. Williams is an important guy to get healthy.

Mullee, who was waiver-claimed from the Yankees, has had a tough time staying healthy. He was having a breakthrough season at age 28 when numbness in his hand shut him down last summer. Brooks was seen as rotation depth after being acquired from Oakland, but he must answer questions about a hip injury. Acevedo likewise had created excitement as a potential bullpen piece before knee surgery ended his 2016 season in April.

Parra, a veteran who has started and relieved, missed last season after Tommy John surgery.

Eye openers

RHP: Casey Kelly , Maikel Cleto , Daniel Corcino , Jhondaniel Medina and Dylan Floro .

LHP: Gerardo Concepcion .

More than Anthony Rizzo , Kelly, 27, was seen as the key to the Adrian Gonzalez-to-Boston trade by San Diego. A first-round pick of the Red Sox in 2008, Kelly is a Tommy John survivor. Cleto has an arm you love (fastballs in the range of 97-99 mph), but Major League hitters have rendered him ineffective by making him throw strikes.

Once compared to Johnny Cueto as a prospect for the Reds, Corcino worked as a Double-A reliever for the Dodgers last year after a series of injuries in 2015 lowered expectations for him. Medina, who turns 24 next week, is the youngest guy on this list. He pitched effectively for four seasons in the Pirates' system as a right-handed reliever, but he never escaped the shuttle between Altoona and Indianapolis.

Concepcion made three Major League appearances over the course of a five-year, $6 million contract, and he timed them well enough to receive a World Series ring. Good work if you can get it.

Phil Rogers is a columnist for MLB.com.