It’s no mystery why athletes love Twitter.

It’s an unfiltered forum in which they can connect with fans and showcase their personalities in 140 characters, pictures or videos without media distortion. Is it surprising that some use it to pitch wares and make a buck?

It shouldn’t be.

Since the days of DiMaggio and Namath, athletes have used their fame to expand their brand and increase their fortunes.

Admittedly, some are better at it than others.

Shaquille O’Neal retired from the NBA in 2011 after a 19-year career. A basketball superstar known for his off-the-court flair, O’Neal had a robust social-media following that included more than 4 million followers on Twitter alone. Endorsement deals with recognizable products such as Oreos, Icy Hot and Toys ‘R’ Us netted him an estimated $15 million.

Not shy to express himself, O’Neal cleverly disguises his “sponsored” tweets as part of his everyday shenanigans.

That kind of incognito branding has grown the former center’s bankroll by about $5 million.

Not all athletes draw such deals. Some athletes are paid by tweet as part of a general endorsement deal, others are paid based on well they draw their crowd of followers to a company website. Those tweets can be worth up to $20,000.

In 2011, former Falcons quarterback Michael Vick famously took some flack from followers who did not appreciate his method of sending paid tweets.

“Check out these prizes from McDonald’s monopoly game,” he told his 800,000 Twitter followers, and what followed was a backlash of angry retorts that had fans questioning his performance on the field instead his play of fast-food games.

Vick wasn’t paid directly by McDonald’s for his influence. Social-media marketer MyLikes, which promises click-throughs by tweeting endorsements from celebrities, had Vick as a client and dispatched the tweet. The company’s list of corporate clients include Atlanta-based Coca-Cola and Chick-fil-A.

Of course, it’s not all business. Athletes on Twitter are highly entertaining. There’s the usual embarrassing post that goes viral.

Take for example Atlanta native Darnell Dockett.

While watching the BCS championship game last season, the Arizona Cardinals defensive end became as moved by Alabama quarterback A.J. McCarron’s girlfriend as game commentator Brent Musburger, who famously gushed about the Miss Alabama USA.

Dockett accidentally sent Katherine Webb a direct message over his 131,000 followers with his phone number to gauge her interest in hitting the town.

What ensued might’ve been bigger than the game score. McCarron tweeted “keep dreaming,” and Dockett boasted that he boosted Webb’s Twitter following from 5,000 to more than 80,000 overnight.

In the end that’s what it’s all about, getting out their message and finding new ways to entertain off the field.