A look at the first half of the Celtics ‘ domination over the Magic in Game 3 …
Three things that the Celtics did well
Making (nearly) every possession count on both sides of the floor
From the time Paul Pierce  hit a contested jumper on the opening possession, it was evident. The Celtics were not going to sit back and allow the Magic steal a game at the TD Garden. They attacked when they could attack, hit the open three when it was there, passed it to the open man effectively. In total, The C’s shot an astounding 51.2% in the first half. At the other end, the Magic rarely took a shot that wasn’t contested in some form. The C’s held Dwight Howard  in particular to just 2-for-7 from the field, and the Magic as a team hit only 23.5% of their shots in the first quarter before raising that to 38.7%, still a low number by most standards.
Rondo being Rondo
Rondo’s 10 points, five assists and one rebound don’t immediately leap off the page like some of his previous stat lines, but it was the highlight reel that he alone created that this first half will be remembered for. His rebound and consequent head fake of Marcin Gortat and easy layup excited the crowd. The hustle and scrap he showed by diving to grab a ball at the feet of Jason Williams  in the second quarter proved again why the Celtics are well on their way to a 3-0 lead in this series. The Celtics have Rajon Rondo . The Magic don’t.
Big Baby’s off the bench
Glen Davis  has performed admirably in these playoffs, but he’s only hit double-digits in points twice before tonight. He already has 10 points in just 11 minutes and has been an absolute spark off the bench. His acrobatic layup with the foul and the little diddy he did afterwards gave the team a jump in the second quarter. Then, the C’s defense barely skipped a beat when he took over for Kendrick Perkins  and Kevin Garnett  in the post coverage of Dwight Howard.
Three things that the Celtics did not do well
Sitting on leads
After jumping out to a quick 7-0 lead, the Celtics appeared to sit back just a little, and before anyone knew it, it was a one-point game again at 7-6. Later, the Magic turned a 43-19 C’s lead into a 43-27 lead in the second quarter. Although the Celtics undoubtedly outperformed the Magic in the first, they can’t allow the Magic to keep pecking away for fear that perhaps the dam will break as it nearly did in Game 1.
Too often trying to make the ‘big’ play
When you have a 20-point lead in the first half, it’s easy for any team to start trying to show off, especially at home. That happened to the Celtics at points in the first half. They tried to blow the roof off the Garden with showboat plays that lead to turnovers. They can’t allow that to happen in the second half or those turnovers could turn costly quickly.
Letdown once Rondo and other starters left floor
As good as Davis and his fellow bench players were, there was a slight letdown in the C’s play once they hit the floor. The C’s actually allowed one more point than they scored when Davis was on the floor. Tony Allen  had a much more difficult time covering Jameer Nelson than Rondo did. The bench players need to maintain the intensity of the starters when they’re on the floor if the Celtics are going to put the Magic to bed in the second half.