Machado and Donaldson have outplayed those others, and this likely will be the choice for a lot of fans. Also, regardless of how the voting goes, both of them will be members of the AL squad in San Diego this summer.
As for starting the game, that's an important, separate and defining honor in itself. In this case, the decision is about as clear-cut as an All-Star vote can get.
It's Machado's turn. Since Alex Rodriguez made the last of his five consecutive starts in 2008, the starting nod has gone to five different players in seven years -- Michael Young in 2009, Evan Longoria in 2010, Beltre in 2011-12, Miguel Cabrera in 2013 and Donaldson in 2014-15.
Even though Donaldson is only 30 years old, and even though he's the defending AL Most Valuable Player Award winner and still one of the 10 best players in the league, Machado has earned the honor.
His fifth full season has seen him realize all the potential the Orioles envisioned for him four years ago when they summoned him to the big leagues and inserted him into the heat of a pennant race.
He was 19 years old at the time, and of all the impressive statistics that can be used to offer perspective on his career, maybe the most impressive is that he's still only 23.
That's a tribute to his talent and to the faith the Orioles had in him as he blew through the Minor Leagues in two years after being the third pick of the 2010 Draft. Machado was drafted to play shortstop and spent most of his Minor League career there. That was the same position his boyhood hero, A-Rod, played. When the Orioles shifted him to third, Machado studied video of Beltre to learn the finer points of the position.
Ironically, Machado has played mostly shortstop this month in the wake of J.J. Hardy's foot injury. As soon as Hardy is back in the lineup next month, Machado will be back at third.
He hasn't just played third base. He has played it as well as anyone in the game. According to the defensive metrics used by fangraphs.com, Machado is a tick behind Beltre among all AL third basemen.
Machado is carving out a serious case that he should be the AL MVP this year. His 2.4 Wins Above Replacement calculation by Baseball Reference trails only Adam Eaton (3.2) and Jose Altuve (2.9) among all AL players.
As for the more measurable numbers, Machado is first in the AL in total bases (98), third in homers (11), doubles (15) and OPS (1.040) and sixth in batting average (.333).
In the Machado-Donaldson matchup, Machado's numbers are slightly better across the board, even though Donaldson has nine home runs and a healthy .874 OPS.
Funny thing is, they're alike in many ways. Both make jaw-dropping, acrobatic plays at third. That's a particularly notable accomplishment since Donaldson, like Machado, also started his Minor League carer at another position (catcher).
Donaldson is seven years older than Machado, and the two of them are no strangers to being among the game's elite. Each has a pair of All-Star appearances and have combined for five Top 10 MVP finishes.
Donaldson has finished first, four and eighth in voting the last three seasons. Machado was fourth in 2015 and ninth in '13.
When the All-Stars gather in San Diego, both of them will be there. Castellanos or one of the others could make it there, too.
But Machado has played well enough to get the ultimate All-Star honor of starting. His time has come.
Richard Justice is a columnist for MLB.com. Read his blog, Justice4U. This story was not subject to the approval of Major League Baseball or its clubs.