After another game slips away, the Celtics could really use a big win

The frustration is real for Celtics fans. Another game of leading the majority of the time and letting it slip away against an upper-tier team. The loss in Oklahoma City was eerily similar to the loss against the Raptors on Friday, and it raises questions about this Boston team's ability to close games and beat contenders.

The Celtics have had no success against some of the league's top talent so far this season, and this trend continued after falling to the Thunder:

You can add the Thunder to that list (whether or not they are "top tier"), making them now 0-6. For a franchise that was pegged as a possible two-seed in the East and the top candidate to compete with the Cavaliers, this isn't a good sign:

I already know what most of you are probably screaming in your head: "But we didn't have Isaiah Thomas for two of those contests and Al Horford for two others!"

This is true, but shouldn't carry too much weight. Boston had a lead for a large portion of many of those games, so there has been an evident problem with closing out games. With no Isaiah, the Celts were having a strong outing against the Raptors, leading by eight at halftime and by as many as 14. On Sunday night (also no Isaiah), Boston was up four on Oklahoma City at the half, and led by 13 points in the third quarter. As we know, they lost both of these games.

When they played San Antonio last month, the Celtics built a 12-point first quarter lead. It looked like everything was going their way, until the Spurs finally took the lead back at the very end of the third and protected their slim lead for the closing 12 minutes. These frustrating results have been happening a bit too much for out liking.

The Celtics are now 8-7 in "clutch games" on the year, but it's what teams compose those eight wins and seven losses that you want to focus on:

The only clutch win against a team above .500 was against the Bulls (Detroit and Indiana currently sit at .500 at the moment), and five of the wins were over teams with eight victories or less on the year (Brooklyn, Dallas, Sacramento, Minnesota, and Philadelphia). Take out those games, and that pedestrian 8-7 record becomes an ugly 3-7.

Again, having Isaiah obviously would've made it easier to close out these last two games. A loss is a loss nonetheless though, so the Celtics are still left in need of a big win. It would boost their confidence and reestablish their credibility as a potential top team in the East (they are the six-seed right now) that can compete with the best talent.

It just so happens that Boston will have an opportunity to prove just that in their next game against the San Antonio Spurs. If they can get redemption on a Spurs squad that always bring their A-game, it would go a long way and finally give the C's a win over a top contender.

Follow Erik Johnson on Twitter: @erikjohnson32

Photo by Brad Rempel-USA TODAY Sports