The Boston Celtics have surprised most with their performance so far this season.

Through 22 games, the Celtics have the NBA's best record (18-4), despite losing free agent acquisition Gordon Hayward to a horrific leg injury in the season opener. Kyrie Irving, who also signed with Boston as a free agent, has been amazing and the Celtics have played stellar defense.

But Celtics head coach Brad Stevens still is not convinced that his team can vie for an NBA championship, per Bill Doyle of the Worcester Telegram & Gazette.

Celtics fans may read that comment and think it a head-scratcher. But Stevens is not completely off base.

The entire NBA has only played about 25 percent of the season and while that's a lot of games, it's still really not that many games.

Boston may have just come out of a 16-game winning streak. But like Stevens said, the Celtics trailed by significant margins in many of those contents.

It says a lot that Boston was able to come back from those games. But it may say even more than a “contending team” allowed itself to fall behind by that much, that many times.

Or, all this could just be coach speak. Stevens is an intelligent individual, and he's figured out an effective way to really speak to his players and get them to buy in.

Still, 18-4 is nothing to sneeze at. If the Celtics continue to win at this rate, Stevens may have to change his tune about his own team.