At the beginning of the season Manchester City didn't show any seriousness in the premier league games; many people didn't expect they will be to get to the first position in premier league., but Manchester City later surprise many people by winning all their games to get to the first position. Manchester United and arsenal started the season well but they failed to remain consistent in thier games expecially arsenal and it was an advantage for Manchester city.
Yeah consistency is a key factor to reach new successes for these teams. Especially Arsenal made a really solid effort during the most part of the season. But on the final weeks of it Arsenal started to mess it up really much. They lost points unexpectedly and this really helped Manchester City catch up with them quite easier.
When it comes to consistency Manchester City have really no match in this league now. Actually Manchester City couldn't make a good start first. But as of one point they started to fix the issues and get positive results more often. After repeating this many times they have become an unstoppable team and Arsenal had nothing to do against that team.