What Trump and Bush did wrong in the debate

Here's what some of the front-runners in the GOP presidential race did wrong in the first debate:

Donald Trump

Donald Trump needed to look presidential in this debate. No boasting or bragging about how he is the greatest businessman ever. He needed to take his image to a deeper level and convince voters that he is more than a reality TV star, but a legitimate contender with a strong command of the issues.

But he didn't. Trump continued with his zingers and the audience laughed. But at one moment in time, Trump actually provided every candidate on that stage with an opportunity to out-Trump, Trump. But no one seized the moment.

Read MoreMacias: Why you should fear Donald Trump

It happened when Trump began bragging about how he took advantage of the laws when four of his companies filed for bankruptcy. I waited for any candidate to remind viewers that this meant small businesses didn't get paid. Trump skipped out on paying people because he was allowed to do it. Sure, it's legal but is it right to not pay your bills when honest work was done for it?

The moderator tried to connect bankruptcies to bad business decisions, but this wasn't about decision-making. It should have been about Trump openly admitting he skipped out on paying people because the law allowed it.

The GOP candidates may have missed their opportunity in the debate, but Trump has now given everyone a sound bite for an attack ad. If the law allowed him to skip out on paying Americans, what would Trump do as president if the law allows his administration to rule the voiceless and powerless?

Jeb Bush

Jeb Bush got caught in the crossfire after Trump attacked his family name. Bush needed to stand tall and maintain eye contact. He should've challenged Trump directly — and forcefully — with both body and verbal language that shows you won't back down. If Vladimir Putin or some other leader attacks the United States, we want our president to fight back. So how did Bush respond to the attack on the family name? I've seen stronger fights on "Gossip Girl." Jeb Bush should have been more forceful in defending his family name.

Rand Paul

Rand Paul let it be known quickly that he came to this debate with boxing gloves. He went after Trump in the opening question for refusing a pledge to not run as a third-party candidate. It was a great opening act, but an hour into debate, Paul started coming across as that angry guy in the bar who rants at politicians because the union just let him go.

But Paul's biggest misstep came when he took on New Jersey Gov. Chris Christie over national security. New Jersey is known for its attitude. You don't mess with Jersey – especially when she is angry. She'll dig her fingernails under your skin and curse you out in words you never heard before. Christie responded with his notorious, condescending attitude.

"Listen Senator, you know, when you're sitting in a subcommittee just blowing hot air about this, you can say things like that. When you're responsible for protecting the lives of the American people, then what you need to do is to make sure you use the system the way it's supposed to work," Christie said.

And when Christie dressed him down a second time, Paul made the classic mistake of looking down at his podium, a visual cue to weakness.

Read MoreWhy Chris Christie may have an edge in the GOP race

Scott Walker

I was curious to see how Scott Walker performed alongside Trump and Bush. Would he have the gravitas to pull off a presidential debate performance? No matter how hard I tried, I kept seeing a casual guy wearing a motorcycle helmet. Somehow, it's not an image I would expect to see for the leader of the free world.

Read MoreVroom! Vroom! Scott Walker needs to suit up

Commentary by Mark Macias, head of Macias PR, a global public-relations firm, that has run media and branding campaigns for politicians, tech start-ups, financial firms, nonprofits and companies. He's also author of the book, "Beat the Press: Your Guide to Managing the Media." Follow him on Twitter @markmacias.