There was a time when the Oklahoma City Thunder were one of the most feared teams in the league and were seen as a perennial title contender. Those days are long gone, as they flew out the door with Kevin Durant during the summer of 2016.

To be fair, no one expected the Thunder to bounce back immediately following Durant's decision to leave Oklahoma City for the Golden State Warriors via free agency.

But, here we are, three years later in 2019, and the Thunder don't seem to have made any progress, which is a bit odd seeing as how they swung a trade for Paul George during the 2017 offseason.

Instead of challenging Durant and the Warriors for Western Conference supremacy, OKC finds itself down 3-1 in a first-round series for the third straight year. In 2017, it was the Houston Rockets. Last season, it was the Utah Jazz. This time around, it's the Portland Trail Blazers.

We can easily look past the Rockets series. Oklahoma City was a sixth seed, and it was essentially Westbrook against the world. Sure, Victor Oladipo was on the roster at that point, but he had not yet blossomed into the star we know today.

So, we can certainly excuse the Thunder for losing to that Rockets team. But to the Jazz last year? A Utah squad that was clearly inferior to OKC in terms of talent? That was inexcusable.

Paul George, Thunder

It's not even like the Thunder put up much of a fight, as they bowed out in six games and looked thoroughly outclassed by a Jazz club led by a rookie in Donovan Mitchell and a bunch of solid role players.

But even then, we could have said that Westbrook and George were still getting used to playing with one another and that having Carmelo Anthony on the roster kind of threw a wrench into things.

It was a reach, but still, it was a plausible theory.

Okay. So the Thunder parted ways with Anthony over the summer, theoretically freeing up Westbrook and George to play more freely within the offense without working about Melo iso-ball bogging things down.

And you know what? Early on, it seemed to be working, as Oklahoma City got off to a great start this season and appeared to be a top two or three team in the West by the All-Star break.

But over the last couple of months, things have unraveled, and now, the Thunder find themselves staring down elimination on Tuesday night as the Blazers try to finish them off in Portland. Chances are, OKC won't be coming back to win this series.

Thunder, Russell Westbrook

So, who is most to blame for the Thunder's struggles since Durant's departure?

A cast of characters share the burden.

Of course, there is Westbrook, who can't seem to harness his ability nor can he seem to understand the fact that he isn't a shooter. Only three of Westbrook's 21 field-goal attempts in Oklahoma City's Game 4 loss on Sunday night came inside the paint, and he ended up making just five shots.

This from a guy who shot 42.8 percent from the floor and 29 percent from three-point range this season and has never been a shooter throughout his entire 11-year NBA career.

Then there is George, who has had his fair share of playoff struggles in recent years. Due to Westbrook's meltdown in last year's Game 6 in Utah, the fact that George scored just five points off of 2-of-16 shooting went relatively unnoticed.

Paul George Oklahoma City Thunder

Now, George certainly deserves a bit of a mulligan for his shaky shooting performance in this series, as he is playing through a bum shoulder, but last spring? George actually escaped warranted criticism.

But then, we have the man who deserves the most blame of all, and that is general manager Sam Presti.

For years, Presti was lauded as a genius and was considered one of the best executives in basketball.

You can't deny his history in the draft. Sure, Durant was a no-brainer, but landing guys like Westbrook, James Harden, Serge Ibaka, Steven Adams, and even Reggie Jackson? Those were home runs, and Presti deserves credit for them.

On the other side of the coin, however, he also deserves blame for his hideous trade history and his inability to put the right supporting pieces around his stars.

Over the final three years of Durant's tenure in OKC, Presti consistently failed to supply KD and Westbrook with a reliable third option. Yes, he did bring in Kevin Martin in the horrible Harden trade, but he then let Martin walk that summer and never replaced him.

Presti has also failed miserably in adding perimeter shooting, which is what has doomed the Thunder in this series.

Paul George, Russell Westbrook, Thunder

A team led by Westbrook absolutely, positively needs shooters all over the floor, and instead, Presti built a roster that ranked just 23rd in three-point percentage this season.

It is not that difficult to put shooters on your roster. They are always readily available, and sometimes, you can get them for cheap.

Not only that, but Oklahoma City lacks depth to begin with, which has been a major problem for the club for years now. For some reason, Presti can't seem to land valuable bench pieces, and that has absolutely killed the Thunder in recent years.

It's about time we start questioning just how good of a job Presti is actually doing with this team. Yes, the Thunder are in the playoffs every year, and they are always one of the league's better teams, but at some point, we have to look at OKC's constant playoff flameouts and start mulling if the problem is not with Westbrook or George or Billy Donovan, but at the top.

Westbrook's legacy is taking a major hit. But so is Presti's.