Maria Sharapova is nothing if not knowledgeable about herself.

For as long as she has been in the public eye, she remained true to that pared-down, hyper-aggressive game (oh, that piercing war cry when she struck the ball!) that earned her a career Grand Slam, albeit one with an asterisk applied due to her late-career suspension for doping. Sharapova is also tough and savvy, endowed with the ability and determination to parlay her on-court success and tightly controlled image into great riches.

But Sharapova, who announced her retirement on Wednesday, alienated as many people as she awed. She had few friends in the WTA, just rivals who existed in her eyes only to be beaten. The reaction to her retirement among her peers: an outpouring of, well, indifference.

The scant testimonials from Sharapova's peers is in stark contrast to the hoo-ha generated when she returned to the tour in April 2017 following a 15-month (reduced from two years) ban for doping. Players, including Simona Halep, Caroline Wozniacki and Agnieszka Radwanska, criticized the rush by tournament directors, including Grand Slam officials, to award the unranked Sharapova wild-card entry into their events. Wozniacki said then, "I feel like when a player is banned for drugs, I think that someone should start from the bottom and fight their way back."

This might seem like a harsh way to approach the departure of the 32-year-old former No. 1 whose signature traits were mental toughness and dedication to her craft. But the record justifies a critical look. After returning from her 2016 suspension for the use of meldonium, a drug that increases alertness and stamina, she went 44-26 in singles, with just one title (she won the minor event in Tianjin, China, in October 2017). She was 5-8 against top-10 opponents, and she made it as far as the quarterfinals at just one Grand Slam event.

True, Sharapova's efforts were also hampered by a chronic shoulder injury, but her struggle with that issue was omnipresent even in her peak years. So it's difficult not to notice the dramatic fall-off in her performance.

At her best, Sharapova's very presence across the net seemed to discombobulate opponents. She struggled with her serve, profligately tossing in double faults, but powered through those passages to take advantage of any flicker of doubt or timidity in her opponents. She prepared to serve by boldly staring across the net for just long enough to allow silence to settle and people -- and her opponent -- to notice. Then she would go to work.

play 1:26 Flashback: Sharapova stuns Serena for Wimbledon title On July 3, 2004, 17-year-old Maria Sharapova upset top seed and defending champion Serena Williams to win her first Grand Slam singles title.

If Sharapova's red-carpet-ready image and astonishing earning power won her legions of admirers, some episodes in her career fueled antipathy toward Sharapova with equally obvious force. One of those occurred in 2006 at the Miami Open. Ranked No. 4 at the time, she faced No. 24 Tatiana Golovin in the semifinals. During the match, Sharapova successfully lobbied the chair umpire to allow her a bathroom break -- an emergency, she said -- as Golovin prepared to serve to stay in the second set.

Then, in the third set, Golovin went down hard as her ankle buckled while she was running full tilt to retrieve a Sharapova blast. As Golovin lay flat in severe distress across the court, having the match-ending injury examined, Sharapova showed no sign of concern or even interest. She stood with her back to the net. She was roundly booed, even as she left the court a winner. Sharapova later said she thought Golovin was merely cramping and added, "I wasn't surprised [by the booing]. It happens in the NFL and everywhere -- the crowd needs entertainment."

It would be nice to counterbalance this anecdote with an example of Sharapova's geniality -- if you could find one. The closest thing might be found among the occasional self-deprecating comments she uttered. She once said that playing on clay made her feel like a "cow on ice."

Sharapova compensated for what skills she lacked by mastering the art of old-school aggression. Sharapova's attitude and actions were something Jimmy Connors, who briefly and unsuccessfully coached Sharapova, understood and applauded. But that's where Sharapova's record against Serena Williams becomes relevant.

Williams is 20-2 against Sharapova, one of those two losses a 2018 French Open walkover. The other Sharapova win occurred way back when a spectacular rivalry with Williams seemed to be written in the stars. After losing to Williams in Miami, Sharapova won their 2004 clash in the Wimbledon final. It was a bitter blow that Williams never forgot. Williams is Sharapova's superior by any metric used to judge the strengths of their games or their combativeness and guts -- as the astonishingly lopsided head-to-head makes clear. But unlike Sharapova, Williams over time became as popular among her peers as she was with fans. She cultivated genuine locker room friendships and became an esteemed role model.

In recent years, it sometimes seemed the chance to somewhat ameliorate the glaring weakness in her resume with a few face-saving wins against Williams was an incentive for Sharapova to continue playing. Her failure to accomplish that will be a mark on her legacy. Sharapova built a career out of intimidating rivals, but Williams forced her into a painful role reversal.

Maria Sharapova mastered the art of old-school aggression throughout her tennis career. AP Photo/Mark Baker

There has never been any love lost between the two fiercest competitors of their time, but they largely kept their antipathy toward each other under wraps. It did poke through briefly in 2013 in the highly publicized "black heart" controversy.

Sharapova has been a role model for a number of young Russian immigrant athletes who have come to the U.S., including recent Australian Open champion Sofia Kenin. Yuri Sharapov, Maria's father, whisked her off to the U.S. at age 7 in 1994 to find opportunity and develop her game with a succession of famed coaches: Rick Macci, Nick Bollettieri and Robert Lansdorp. Sharapova has been a permanent resident of the U.S. since 1994, but she is proud of her Russian identity and represents the nation in international competitions (she was the flag-bearer for Russia in the 2012 Olympics).

There will be no Tokyo Olympics for Sharapova, it appears, at least not as a competitor. She might turn up there as a commentator, as she did for the Sochi Winter Games in 2014. In her retirement announcement in Vanity Fair and Vogue, Sharapova wrote:

"Looking back now, I realize that tennis has been my mountain. My path has been filled with valleys and detours, but the views from its peak were incredible. After 28 years and five Grand Slam titles, though, I'm ready to scale another mountain -- to compete on a different type of terrain."

Analogy aside, the declaration suggests Sharapova is eager to segue fully into the business landscape she has explored, off and on, during her career. We'll see how the qualities she brought to bear in tennis work in an arena where relationship-building and respect for peers and competitors is important. Her self-knowledge is likely to come in handy in more ways than one.