I hd a good chuckle at the massive rage thread on reddit with people claiming Barnes brutally tackled Matic before the red card. I watch the replays and Barnes was just passing, but apparently not everyone realizes passing the ball usually requires moving one's leg forward.
He did brutally tackle him though. He followed through with his foot way too hard. For me it was a clear red card for both players, but the referee obviously missed it. If he hadn't, a yellow would have been the very least.