Dallas players Matt Hedges and Kellyn Acosta knocked heads during a match against New York City FC last weekend, a collision so intense that Hedges required six stiches at halftime and had to change his jersey because of the blood.
Yet some viewers questioned whether either player was sufficiently checked for a concussion.
"I didn't know I was bleeding until everyone started saying it was," Hedges told reporters after the game. "They bandaged it up so I could go back in and then they stitched it up at halftime. ... I love to play and I don't really care if I am hurt or whatever, I just want to be out there."
Another scary incident occurred in the first half of Atlanta's game at Portland on Sunday. United's Yamil Asad was hit in the head by a ball kicked at close range and dropped limp to the turf. He returned to the game moments later.
Referee Alan Kelly said via a pool reporter that the "Atlanta medical staff determined after the check that he was fit to play. They sent him to the fourth official after the check."
But again, there were questions about whether Asad was properly evaluated.
Major League Soccer has an ever-evolving concussion protocol that has been developed by the league's 12-person Concussion Program Committee, which includes prominent neuropsychologist Dr. Ruben Echemendia.
The protocol is similar to the U.S. Soccer Federation's policy and guidelines adopted by other sports leagues. Players are evaluated using the Sport Concussion Assessment Tool, or SCAT, which is also used at the international level by FIFA. In addition to on-field assessment, concussion identification and return-to-play guidelines, the MLS protocol includes baseline testing.
New this season is the league's use of spotters who monitor each league match to help club medical personnel identify possible concussion cases.
"It's an area we're very focused on in ensuring that we're taking the best science possible and creating the best protocol we can from that science," MLS Deputy Commissioner Mark Abbott said.
Abbott said that in both cases last weekend, medical personnel made the on-field determination that the players could go back in the game. Also in both cases, additional evaluation was done later, either at halftime or after the match, and neither player was determined to be concussed.
In Asad's case, the physician for the Timbers raised the question about whether he should have been subject to additional on-field evaluation. The league is looking into whether further evaluation should have been conducted during the game, although Asad was cleared to play by further testing at the half, Abbott said.
It's up to the individual teams to follow the concussion protocol. That's something that former player-turned-broadcaster Taylor Twellman pointed to on Twitter this weekend.
He posted: "Until @MLS holds their franchises accountable when they blatantly ignore the concussion protocol then serious progress can't be made."
Twellman is passionate about the issue. His MLS career was ultimately ended because of the lingering impact of a serious concussion. He founded the THINKTaylor foundation, which seeks to promote concussion education, safety and awareness.
Abbott said that if teams do not follow league policy, they are subject to discipline.
"If there is a violation of any league rule or policy, including this one which is very important, the people who are responsible to that violation are subject to sanctions, which could be fines or a variety of other things," he said.
MLS was part of a head injury and concussion summit just last month with U.S. Soccer and the National Women's Soccer League.
GAME OF THE WEEK: Could this be the week that FC Dallas finally loses? The team has a nine-game unbeaten streak heading into Saturday's match at home against the San Jose Earthquakes. But the defending Supporter's Shield winners still trail Toronto in overall points. Dallas is coming off a 1-1 draw at home over NYCFC.
"It's our goal all the time to get a good result, but this league is built with many good teams and many players that are playing in the MLS now that show that it's not going to be easy," Dallas coach Oscar Pareja said afterward. "Getting one point sometimes is going to be a luxury, got to tell you that, and probably this game is one of those."
The Earthquakes hosted Orlando on Wednesday night before traveling to Texas. San Jose has shown some spark this season with a 3-0 win over the Timbers.
BEST OF THE REST: Speaking of Toronto, the Reds visit the New York Red Bulls on Friday. Toronto is 7-1-4 this season paced by Jozy Altidore with six goals and Victor Vazquez with a league-leading eight assists.
But Toronto has been hit by a pair of key injuries. Forward Sebastian Giovinco has a quad strain and is expected to miss three weeks. Defender Nick Hagglund has a torn MCL in his left knee and will miss up to 12 weeks.
HONORS: Columbus midfielder Justin Meram was named MLS Player of the Week after scoring three goals in the Crew's 3-2 victory over the Montreal Impact last Saturday. It was his first career hat trick.