The Boston Celtics signed Al Horford to a four-year, $113 million contract this summer -- the biggest free-agent pact in team history -- and he'll hold down one spot in the team's frontcourt for the 2016-17 season.

The question to our panel on Day 4 of our Celtics Summer Forecast: Who will start alongside Horford in Boston's frontcourt?

Panelists were given five choices: Amir Johnson, Kelly Olynyk, Tyler Zeller, Jonas Jerebko and Jae Crowder. Our 21 local bloggers essentially made it a two-horse race, splitting their votes between just two of those options.

Johnson earned 52.4 percent of the vote, while Olynyk got the other 47.6 percent.

This writer's thoughts? Our vote assumes that Olynyk, who underwent shoulder surgery in mid-May, is healthy enough to handle a starting role. Johnson might get the spot by default at the start of the season because Olynyk has suggested it will be at least mid-October before the team reevaluates his recovery progress. If everyone is healthy, the idea of adding Olynyk's shooting and floor-spacing alongside Horford is a very intriguing possibility, though rebounding might be a concern in that instance.

While no one on our panel voted for it, this writer remains curious about the sustainability of a three-guard lineup. If Marcus Smart shows he's making a leap this year, we'd be interested to see an Isaiah Thomas-Avery Bradley-Smart perimeter with Crowder and Horford the bigs in a switch-happy lineup. Boston would be able to roll in a second unit that would feature Johnson and Jerebko at big-man spots with minutes for Jaylen Brown on the wing, and maximizing Boston's guard depth with guys such as Gerald Green and Terry Rozier in reserve spots.

Again, rebounding is a concern by going small, but it's not like any of Boston's current bigs in the post-Jared Sullinger era is elite at that skill.

Training camp and the exhibition slate should help determine if three-guard lineups are feasible or if the Celtics should simply stick with the more traditional pairings that guys like Olynyk and Johnson could offer.

Here's how our divided panel voted:

Jay King, MassLive (Olynyk): What do the Celtics need more than anything? Shooting. The easiest way to add that is by shifting Olynyk into the starting lineup, leaving Brad Stevens with two floor-spacing bigs in his first five. That would help Isaiah Thomas, who should have more lanes to dance through this season. Johnson could be another starting option, but I suspect Stevens will stagger his two best rim protectors (Horford and Johnson) next to a crew of skilled power forwards (Olynyk, Jerebko and Crowder). That rotation should push Boston's offense into the top 10, if not better, while maintaining the defensive foundation.

Bill Sy, CelticsBlog (Olynyk): Josh Smith. Paul Millsap. And now, Olynyk. At his introductory news conference, Horford went out of his way to name-check Olynyk as one of the players he's looking forward to playing with. He shot over 40 percent from behind the arc last season and had the highest net rating of any of the rotation players. Horford was a four time All-Star in Atlanta flanked by a stretch-4, so the Celtics should be fully invested in giving Olynyk a shot at starting power forward. And if they like what they see in training camp, he's eligible for a rookie extension before the season starts.

Ryan Bernardoni, CelticsHub (Olynyk): Jerebko might be a better partner, but Olynyk is the better player and has tenure. I expect him to get the first shot at starting.

Kelly Olynyk's outside shooting makes him an intriguing option to start and help spread the floor. Jeff Hanisch/USA TODAY Sports

Sam Sheehan, Celtics Reddit and CLNS Radio (Johnson): I struggled the most with this question, simply because the most likely candidates (Jerebko, Olynyk and Johnson) all have a "pick two" relationship when it comes to shooting, rim protection and rebounding. Jerebko, aka Swedish Larry Bird, will give you effective rebounding and shooting but will struggle to defend the rim. Olynyk can provide shooting, size and surprisingly solid positional defense, but he can be bullied on the boards. A healthy Johnson will rebound, protect the rim and roar down the lane, but he doesn’t offer the floor spacing. I landed on Johnson, because I think that "not playing center all the time" was part of the Celtics' pitch to Horford, and I think Olynyk and Jerebko’s shooting could help a bench that might be hurting for scoring. However, I think that we could see Brad tinker a bit, given the flexibility he has, from matchup to matchup. I also wouldn’t be shocked if Crowder was starting games at the 4 before the end of the season.

Rich Jensen, Red's Army (Johnson): I think, initially, Stevens is going to start Horford as a straight-up swap for Sullinger. He's another more or less positionless player (think Crowder or Smart) who will fit in great with Stevens' motion offense and team defense concepts.

Jeff Clark, CelticsBlog (Olynyk): I like pairing Olynyk next to Horford to give the starting lineup more shooting. Then Johnson can sub in for Horford and Boston will always have a rim protector on the court. Crowder and Jerebko can play some small-ball 4, too.

Dan Greenberg, Barstool Sports (Johnson): I think Johnson gets the start, simply because the starting unit is going to need to address the rebounding they lose with Sullinger's departure. Defensively, Johnson can protect the rim and allow Horford to spread the floor and play further from the basket, which is a style he seems to prefer. Not to mention Johnson runs the floor well, and he doesn't require you to run plays for him to have an impact.

Jon Duke, Celtics Stuff Live on CLNS Radio (Olynyk): Perhaps it's wishful thinking on my part, but I'd like to see Olynyk become the frontcourt partner paired with Horford. I'm not sure if Olynyk has the foot speed to stay with the quicker power forwards in the league, but his shooting might allow the Celtics to start Smart and bring Bradley off the bench.

Sean Penney, CelticsBlog (Johnson): Horford has always preferred the power forward position, so starting him alongside someone capable of manning the center spot makes sense. His rebounding numbers have also slipped the last few years, in part because he's playing away from the basket more on offense. Johnson cleans the glass as well as anyone on this team, so putting him next to Horford would help Boston control the boards.

Justin Poulin, Celtics Stuff Live on CLNS Radio (Johnson): Johnson starts but does not finish the season in the starting lineup. Stevens struggled with continuity at the outset last year but is smart enough to avoid that fate this season. Horford fits in quickly as an upgrade over Sullinger, but, by starting Johnson, the Celtics can pick up where they left off and focus on defense first. Stevens first works to get the most out of integrating Horford and allows Olynyk to catch up after offseason shoulder surgery. From there, Stevens moves on to spacing the floor and managing Johnson's minutes by tinkering with Olynyk/Jerebko at the 4, possibly also going small with Crowder at the 4 and a 3-guard lineup for certain matchups.

Alex Kungu, CelticsBlog (Olynyk): I like the idea of Olynyk starting because it allows Boston to always keep one rim protector on the floor with Johnson coming off the bench. This also maximizes spacing by surrounding Thomas with capable shooters, and giving guys such as Crowder and Bradley more space to cut. Another advantage is having two bigs through whom you can run the offense allows Thomas to play more off the ball where he has proved to be a great shooter.

Mike Dynon, Red's Army (Johnson): Last season's starting five on most nights was Thomas, Bradley, Crowder, Johnson and Sullinger. It seems logical that Stevens would again go with that group, exchanging Horford for Sullinger, and keeping Olynyk with the second unit to spread the floor. With all due respect, we don't want to see Jerebko or Zeller start because that would probably mean someone was injured.

Lachlan Marr, CelticsBlog (Johnson): I’d love to see Jerebko crack the starting lineup, especially after his performance in last season's playoff series against Atlanta. But I think Johnson is a more realistic and sensible starter for the Celtics. Not sure who would be the center and who would be the power forward with Al and Amir as starters, but I don’t think it would matter in Stevens' system where versatility is always an advantage.

Sam Packard, WEEI.com (Olynyk): You want to put as much shooting as possible around Isaiah. Plus a back-up unit featuring Jerebko and the "Big Dog" Amir Johnson feels like too much fun.

Wes Howard, CelticsBlog (Olynyk): Stevens has consistently espoused the value of playing groups of players that do well together. Splitting up the team's two rim protectors (Horford and Johnson) and the two distance shooters (Olynyk and Jerebko) provides a balance that lets Boston really utilize its depth.

Jake Keaney, CelticsBlog (Johnson): Given that Johnson has the most experience as a frontcourt starter for the Celtics, I would expect him to be Horford’s partner in the starting lineup for the start of the season. As the season progresses, we’ll have to see whether Stevens and his staff stick with Johnson’s defense and experience or opt for the floor-stretching capabilities of Olynyk or Jerebko.

Jared Weiss, CLNS Radio (Olynyk): Olynyk has unfinished business. He was one of the league’s most efficient 3-point shooters heading into the All-Star break, but injuries tarnished the second half of his season. The Celtics dreamt of a starting frontcourt with Olynyk and Sullinger last year, but now can make it work even better with Horford. Olynyk is an ideal starting 4 with his spacing on offense and improving footwork on defense. Crowder will finish many games at the four, but the Celtics will continue to start two bigs. This allows Johnson to replace Horford as the defensive anchor with the second unit and ensure the Celtics can always have a knockdown shooter at the four.

John Karalis, Red's Army (Olynyk): Spacing! Spacing! Spacing! I like Thomas, Bradley and Crowder playing the 1-2-3, so adding Olynyk with Horford means all five guys need to be respected on the perimeter. Then when Horford and Thomas run a pick-and-roll, IT will have more room to operate and a lot more options to burn poor defensive decisions, including Olynyk parked in the corner taking 3s.

Ben Mark, Red's Army (Johnson): I love Crowder at the 4, but I don't believe Stevens will go to that small-ball lineup consistently. Johnson/Horford fortifies the back-end of the Celtics' defense. Both guys excel at setting good screens offensively and then finishing off the roll. I'm a little worried about spacing, but both guys, especially Horford, can step out and stretch the defense.

Mark Van Deusen, CelticsLife (Johnson): Crowder will definitely see time as a small-ball power forward, but Stevens isn't going to begin games that way. I expect both Olynyk and Johnson to make their fair share of starts. Olynyk was the best 3-point shooter on the squad last year, but he's not much a rebounder. Horford averaged only 7.3 boards per game last season, so he's going to need some help. With Sullinger gone, Johnson is the best option.