Cardiff had just gone 2 - 1 up when McPhail kicked the ball away to earn a silly 2nd yellow card. Cardiff with 10 men had to contain the home side and did so to earn a draw but a victory was there for the taking before McPhails madness.
He told the club website: "I want to apologise to my team-mates, the club and, most importantly, the fans.
"I fully appreciate just how much I've let [them] down. I reacted in the heat of the moment. I know that going down to 10 men probably cost us the win."
The 28-year-old Republic of Ireland midfielder continued: "Anyone that knows me will know that it's totally out of character for me to do something like that and as captain of the team, I should know better.
"I've apologised to the lads and the staff after the match but felt I owed it to the fans to front up to them as well.
"Once the ban is over, I'll come back and let my performances pay everyone back and help the club pick up some more wins."
He now misses the home game with Preston on Saturday and the away match at Burnley a week tonight.