By Brian Robb, CBS Boston

BOSTON (CBS) – One of the biggest surprises of the 2015 NBA Draft was watching Texas forward Jonathan Holmes not be one of the 60 players selected by 30 NBA teams.

Most experts projected the 6-foot-9 hybrid forward would be scooped up in the bottom of the first round, and DraftExpress.com listed the 22-year-old as the 24th best prospect in the entire draft class.

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A dip into the second round for Holmes would have been understandable, but seeing most teams pass on the forward twice? That was an unexpected scenario.

Going undrafted, as opposed to being taken in the second round of a draft, does have its benefits sometime. One of them is choosing what team you play for in NBA Summer League. The Celtics had a roster packed with NBA prospects, but not a ton of bodies in the frontcourt, so Holmes would have a chance to show what he can do by deciding to play with Boston. Additionally, he talked about the appeal the team’s coaching staff had to him.

“I just know they have the best coaching staff,” Holmes said last month in Las Vegas, “And I feel like I have a good opportunity to play here and show what I can do. Just Brad Stevens and his staff — he’s one of the best coaches coming up right now. So they all really know the game really well, and they help explain it to us and break it down to us in a way we can understand it. It’s been a lot of fun.”

By electing to suit up with a stellar Celtics summer league team in Orlando and Las Vegas, Holmes chose well. He was surrounded by a talented group of guards, which allowed him to play to his strengths, and he proved to be a bright spot on the roster as a stretch-four.

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The former Longhorn averaged a pedestrian 10 points and five rebounds in eight games but posted promising numbers from the perimeter, as shown by his 48.1 percent shooting from the field and 46.4 percent accuracy from three-point range.

This superb play would have normally earned Holmes a realistic chance to compete for a roster spot at Celtics training camp this fall, but he fell victim to the team’s logjam of bodies. With the addition of Perry Jones and Zoran Dragic, Boston already has 17 guaranteed contracts on the roster with only 15 spots available for the start of the season.

The Celtics’ brass surely wanted to invite Holmes to compete for a spot in the team’s training camp this fall, but Holmes understandably wanted just more than an opportunity from an NBA team. He wanted some security, and he got that late Saturday as Shams Charania of Real GM reported that Holmes had agreed to a deal with a “sizable” guarantee from the Los Angeles Lakers.

It’s a tough situation for Boston since the coaching staff that Holmes raved about will not get a chance to benefit from his play during the season. However, with Danny Ainge remaining patient with his roster and not rushing into any blockbuster trades, open spots for any undrafted free agent are going to be hard to come by. Still, Boston is a team in need of capable three-point shooters, especially for bigs. Holmes showed off that talent in a limited sample size in summer league, but he could end up being a helpful piece for the Lakers in the long run.

With Holmes heading to Boston’s hated rival, Celtics fans will head into next season hoping that Boston sees solid play out of a recent acquisition Perry Jones, one of the additions that kept Holmes from potentially sticking around for the regular season.

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Brian Robb covers the Celtics for CBS Boston and contributes to NBA.com, among other media outlets. You can follow him on Twitter @CelticsHub.