Much of the hype surrounding the Boston Celtics this offseason has been positive. And our Celtics Summer Forecast panel came up with plenty of different responses last week when we asked for reasons to be excited about the upcoming season.

For Day 13 of our Celtics Summer Forecast, we flipped the script and asked, what's your biggest concern about the Celtics?

Maybe not surprisingly, more than half of the responses from our panel of local Celtics bloggers included the word "shooting." The Celtics really struggled shooting the ball last season, especially beyond the 3-point arc, and our panel is worried they didn't make obvious upgrades to that area this summer.

It's hard to argue with, though it's worth noting that Boston still ranked in the top half of the league in offensive rating despite its shooting woes. It seems impossible that the team could struggle as much as it did last season with the talent it has.

This writer's vote? We'll go with rebounding. The Celtics ranked 25th in defensive rebound percentage last season and let its best pure rebounder walk away in Jared Sullinger. Boston's undersized bigs are going to have to find a way to make up for his absence on the glass and the team's rebound-happy guards will have to continue to help out in that area.

The Celtics may have one of the better defenses in the league next season, but it's hard enough to get one stop in the NBA. Boston can't routinely be giving up second-chance opportunities that come with failure to compete on the defensive glass.

Some of our panel's responses:

Brian Robb, CelticsHub (Shooting): The Celtics have finished in the bottom four of the NBA for the past three straight years in 3-point shooting percentage and did little to help their cause on that front this offseason. Al Horford is a big addition, but he's a below-average shooter (34.4 percent) from long distance. Combine that with taking a work-in-progress shooter (Jaylen Brown) with the No. 3 pick in the draft and floor spacing will continue to be an issue some nights unless the team sees some serious internal improvement.

Tom Westerholm, MassLive (Expectations): Look, there's no reason adding Horford should do anything but make the Celtics much better, but this is still a team that will need to grind out wins. I don't expect a Brad Stevens-led team to lose its edge, but after years of overachieving, what happens with the Celtics (and the conversation around them) when expectations are high for once?

Jon Duke, CSL on CLNS Radio (Shooting): It's all about the thing Lil Jon brought to everyone's attention: "SHOTS! SHOTS! SHOTSSHOTSSHOTS!" Horford's presence helps to space the floor in clutch situations at the 5, but the 2016 Celtics succeeded in the clutch at times due to Evan Turner's playmaking and ISO abilities. For a raft full of reasons, they need to edge closer to league average to be able to advance deeper in the playoffs.

Dan Greenberg, Barstool Sports (Second-unit scoring): Say what you want about Turner, but he was crucial to the offensive performance of the second unit. When you take a look at what the Celtics will trot out there this year, there is so much uncertainty. Will Terry Rozier's summer translate to the regular season? Will Marcus Smart's shooting woes persist? Can Jaylen Brown shoot 40 percent? The other part of this equation is, if Kelly Olynyk earns a starting role, there really is not shooting on the floor once the bench comes in. The Celtics had one of the highest scoring benches in the entire league last year, and they'll need a similar performance if they want to go anywhere this year.

Ryan Bernardoni, CelticsHub (Wing shooting): It looks like the Celtics will continue to be a bizarrely inverted team with great shooting big men and strong rebounding smalls. Swapping Jared Sullinger for Horford creates the potential for a real team rebounding problem but the addition of Brown and integration of Rozier can hopefully mitigate that, like Smart did last season. The wing shooting issue is harder to get over. Internal improvement from Smart might help, and the move from Turner to Rozier almost certainly will, but that's just a change from terrible to below average. Coach Brad Stevens has found ways to deal with this in the regular season; in the playoffs it's a crushing weakness.

John Karalis, Red's Army (Olynyk never takes a step forward): Olynyk seemed to find his groove before the All Star break last year but then a shoulder injury derailed him and he faded. It's too much to ask the December/January Olynyk to show up and shoot 47 percent from 3, but if he can get out there and hit 40 percent while displaying some assertiveness on offense, then this could be a special season for Boston. My concern is that Olynyk only shows flashes moving forward and doesn't get the level of consistency that takes him from "he could be dangerous" to "you can't help off of him."

Justin Poulin, CSL on CLNS Radio (Frontcourt depth): The addition of Horford is an obvious upgrade to Sullinger, but the depth of the frontcourt on this roster is unchanged. Stevens is not afraid to go small and run three guards out onto the court, which does help mitigate those concerns, but the truth remains that an injury to any one of Horford, Amir Johnson or Olynyk could spell trouble for this panel's win total predictions. Zeller is always ready to play, but Mickey will have to work through nerves at the NBA level. Jonas Jerebko could be called on to play PF and did so admirably in the postseason against the Hawks. Swedish Larry Bird could spell Olynyk at times, but certainly not Horford or Johnson. Horford has played less than 30 games in two of his last five seasons, but is coming off the first of his career where he appeared in all 82 games. Johnson struggles with plantar fasciitis; limiting his minutes increases the likelihood he will be at full strength in the postseason. Olynyk has missed 12, 18, and 13 games respectively through his first three years in the league. That number should have been higher last year as we watched him struggle through a shoulder injury that ultimately required surgery this summer. I'm not trying to go all doomsday on everyone, but I have no doubt this is an area of concern worth keeping an eye on.

Mike Dynon, Red's Army (Expectations): Wow, the Celts snagged Horford, everyone has them ranked near the top of the East, and they're on national TV almost every week! Now they just have to handle the pressure, because falling short of expectations is almost worse than having none at all.

Sam Packard, WEEI (Rebounding): Sullinger may not have been in the best shape, but darn could his rotund posterior box out. Horford isn't known as the greatest rebounder, so I expect the front line to struggle some, especially against bigger teams. Maybe high-flying guards like Rozier and Smart can help out from the backcourt, but I don't see that as a sustainable long term solution.

Bill Sy, CelticsBlog (Sullinger blowing up in Toronto): Danny Ainge has been so good at sucking the marrow out of every asset in his war chest, but let Sully walk to the Raptors on a one-year deal for a mere $6 million. I’m not the biggest Sullinger fan, but every outlet pass he throws right on the money; every rebound he rips down over a bigger player, and every pick-and-pop he hits will be painful to watch. Sully failed to put it all together in Boston, but I’ll still root for him.

Ian Keilty, Dirty Water Media (Shooting, Closing out games): The Celtics had two needs going into the offseason: shooting and a big man/rim protection. They addressed the need for a big man by getting Al Horford. Horford can shoot better than any of the Celtics' other bigs, but adding him doesn't fill the need for shooting and neither did adding Gerald Green. Losing Turner means that the Celtics lost their closer. We saw last year that it was tough for Isaiah Thomas to close out games when everyone in the arena knew the ball would be in his hands with time running out. Horford is great, but I don't see Stevens using him in a "closer" role, so who will get the ball with the game on the line?

Jake Keaney, CelticsBlog (Shooting): Since the players earning minutes at the guard position haven’t changed much, I’m worried that the Celtics won’t be able to improve last season’s 28th-ranked 3-point percentage without the roster’s current guards putting in some serious work this offseason. Just adding Green won’t be nearly enough.

Mark Van Deusen, CelticsLife (What if Turner + Sullinger > Horford?): Sullinger was the Celtics' leading rebounder last year at 8.3 per game, even though he only logged 23.6 minutes a night. Before Isaiah Thomas' arrival in Boston, there were times when Sully was arguably the team's best player. Turner was the backup point guard and the only guy besides Thomas who could create his own shot in crunch time. What if the loss of Sullinger and Turner is a bigger deal than we expect? Is it possible the addition of Horford won't make up the difference? Rebounding is at the heart of this concern. Horford pulled down just 7.3 boards per contest last season, despite averaging 8.5 more minutes than Sullinger.

Sam Sheehan, Celtics Reddit and CLNS Radio (Shooting x 10^14): I've seen "rim protection" floated as a problem, but when you have a top-5 defense, it's tough to say that much is wrong. Maybe, sans Sullinger, the rebounding will be an issue, but Johnson and Jerebko are both good when healthy and the guards really help out. For me, shooting is the answer and I don't think it's debatable. The Celtics were 28th in 3-point percentage last year and that's a problem when you are a pace-and-space team. Here's the list of above league average (35.4 percent, per Basketball-Reference.com) shooters the Celtics had last season: Jerebko, Olynyk, Bradley, and Thomas. That's it. If the Celtics want to make a leap to semi-contention, they have to get to at least average 3-point shooting.

Rich Jensen, Red's Army (Shooting): Frankly, I'm starting to get worried about the Celtics' consistently poor shooting. This is a team that had a top 10 offense, while being 24th in the league in effective field goal percentage last year. I can't help but look at the wasted possessions and wonder how good this team would be if they had even average shooting.

Ben Mark, Red's Army (Contract questions): When the media descends upon Waltham at the start of camp and players hold court with the microphones in front of them, how will those like Thomas, Crowder and Bradley respond to questions about the money that inundated free agency this past summer? Tyler Zeller, the Celtics' fourth or fifth big, is making more than all three of the aforementioned Celtics. Will that have any sort of impact? Odds are, it won't, but one comment taken out of context can be blown up and might fester. A trademark of Stevens' teams through three seasons has been the ability to come together from a chemistry standpoint. Hopefully that will continue.

Jared Weiss, CLNS Radio (Open 3-pointers): Most of last year’s problems could have been diminished by an even moderate improvement in 3-point shooting. The Celtics shot 32.8-percent on open 3s last season, per NBA.com, tied with the Pistons for second-worst in the NBA. They didn’t acquire a wing shooter that will impact the rotation, so the growth will have to come from players like Smart -- the worst 3-point shooter in the league by a comfortable margin -- and Crowder, who went cold battling injury late in the season. Horford will be an upgrade over Sullinger from deep, but the problem is roster-wide and will need a cure from every corner of the rotation.