Are fans right to be upset that Serena Williams beat American Pharoah for SI Sportsperson of the Year?

Sports Illustrated announced Serena Williams as its sportsperson of the year on Monday, and a lot of people seem to be upset about it.

They wanted a horse.

To be fair, American Pharoah is not just any horse. He is horse racing's first Triple Crown winner in 37 years. And he won the magazine's readers' poll for the award.

@SInow @SI_ChrisStone @serenawilliams American Pharoah is the winner-hands down. You people are ridiculous.
— Looise (@Looise1) December 14, 2015

Of course, a strong argument can be made for Serena as well — one that goes beyond the obvious points that the award is called the sportsperson of the year and only humans have won it since its inception in 1954.

Williams won 53 of the 56 matches she played this year, including three of the four Grand Slam events, and held the No. 1 spot in the WTA rankings every week.

@GPatty_ @SInow Yup: She competed all year and lost exactly 3 matches. The horse competed 8 times and lost 1. 53–3 > 7-1.
— Ken Childs (@TheKenChilds) December 14, 2015

I know that horse can't beat Serena in tennis. I'm not entirely sure Serena would lose to that horse in a race.
— Ol' QWERTY Bastard (@TheDiLLon1) December 14, 2015

Sports Illustrated's Christian Stone pointed out that the 34-year-old Williams was also recognized for career achievements, which include 21 Grand Slam titles, as well as something that goes beyond sports.

"We are honoring Serena Williams too for reasons that hang in the grayer, less comfortable ether, where issues such as race and femininity collide with the games," Stone wrote. "Race was used as a cudgel against Williams at Indian Wells in 2001, and she returned the blow with a 14-year self-exile from the tournament. She returned to Indian Wells in ’15, a conciliator seeking to raise the level of discourse about hard questions, the hardest ones, really."

Serena should have won this award for her return to Indian Wells alone tbh.
— *Partition Beat* (@Brillianthony) December 14, 2015

SI states that the sportsperson of the year award goes to "the athlete or team whose performance that year embodies the spirit of sportsmanship and achievement." That puts American Pharoah at a clear disadvantage since horses can't really display sportsmanship.

But he did treat sports fans to something many of them hadn't seen in their lifetimes -- the Triple Crown. Meanwhile Williams came up short in winning what could be considered her sport's equivalent, the calendar-year Grand Slam.

I love how you give it to someone who "almost" won a grand slam when you could've given it up to an athlete who actually did. @SInow
— Juanita Webb (@NitaMarie65) December 14, 2015

(2/2) disappointed that #AmericanPharoah the only nominee to actually win a #GRANDSLAM didn't get it. Why promote online poll? @SInow
— Ashley Zayat (@AshleyZayat8) December 14, 2015