Congressional Country Club in Bethesda spent two years reworking its venerable Blue Course, moving tees and traps, altering the shape of fairways and re-engineering all 18 greens, equipping them with sophisticated drainage and cooling technology.

The goal was to provide as stern a test as possible for the best golfers of the world at the 2011 U.S. Open.

Those efforts were largely undone this past weekend, as what is traditionally golf’s most arduous event was turned into a relative breeze. Twenty players finished under par, a total exceeded just once in the 111-year history of the tournament. On Sunday, in the final round — when an Open course is supposed to be at its most difficult — 32 players broke par. The previous high for a final round was 18.

The low-scoring spree raised some questions about whether Congressional — which has also hosted the Open in 1964 and 1997 — should stage the tournament again.

“Is Congressional worthy?” asked two-time champion Curtis Strange on Monday. “Well, we certainly didn’t find out this week.”

The reason for Congressional’s easy play was largely explained by an unlikely combination of unfavorable weather — two early-season heat spells before the tournament followed by drenching evening rains during the event. The weather left the greens too soft and the rough too short — a combination that left the course vulnerable and exposed to professional golfers at the top of their game.

Not that golf fans were disappointed. Nearly 250,000 people turned out to watch at Congressional last week, and on Sunday 22-year-old Rory McIlroy of Northern Ireland was crowned champion after a record-setting performance.

Indeed, officials said shortly after the event concluded that they saw no reason why the Open shouldn’t return to Congressional, perhaps in 2026, when the United States will be celebrating its 250th birthday. “The golf course certainly is a great test, and so there’s no reason we wouldn’t come back,” said Mike Davis, the United States Golf Association executive director.

Before that decision is made, however, USGA officials will take a measure of how Congressional stood up to the test in 2011, and whether the changes made to the course over the past two years worked.

So what happened?

The reasons lie in a confluence of agronomy, meteorology and strategy. Start, first, with the grass.

In July 2009, Congressional began replacing all the greens on its Blue Course, switching from one type of grass, poa annua, to another, bentgrass, that would hold up better in Washington’s long, hot summers. The move was made not specifically because the club was preparing to host the Open — indeed, it was a long-term decision about the health of the greens — but the USGA supported the decision.

Earlier this spring, officials from both the club and the USGA were pleased with how the greens were coming around. Enter, though, meteorology. In the two weeks prior to the Open, Washington experienced two periods of unseasonably high temperatures, including consecutive days a week before the Open in which the heat index reached above 100 degrees. The impact on the turf was immediate. Suddenly, cutting the greens as short as the USGA wanted — essentially, making them as fast as required to test the world’s best players — would mean putting the grass in jeopardy.

“It’s just like a human being,” said Mike Giuffre, Congressional’s director of golf course maintenance. “When you’re hot and sweaty, you’re not going to go out and run a marathon. So we backed off, knowing that we were going to have a situation where it was really too hot to do a lot of stuff without putting some stress on the greens.”

Had the greens been older, though, their root structure would have been more established. The heat would have had an effect, but it likely would have been more manageable.

“I think we — both Congressional and the USGA — probably wish we’d redone the greens one year earlier, and had another year to get the roots deeper and that sort of thing,” said Ben Brundred, the co-chair of Congressional’s U.S. Open committee. “They certainly would have weathered the conditions better. But they still would have been slow.”

That’s thanks to another bit of meteorology. During the tournament, Congressional took on almost an inch of rain, mostly from overnight thunderstorms. Water softened greens that the USGA wanted to be hard. Thus, shots that might have bounced away – had the greens been as the USGA hoped – settled in nicely, and putts that were supposed to roll swiftly slowed down.

“It’s an outdoor sport,” Davis said. “So sometimes this happens. This isn’t the first time something like this has happened.”

Davis has been responsible for setting up U.S. Open courses — determining how high to grow the grass, where to put the holes, how long to play the course — since 2006. He has been widely praised by players for making the courses difficult but fair. At Congressional, though, there is a sense that the USGA made a series of strategic errors.

“Two things,” said Strange, who won the tournament in 1988 and 1989. “Grow the rough, and play the whole golf course. They’re big boys. They’re stronger than we ever were. Let’s make it a challenge.”

When Congressional hosted the Open in 1997, the rough was six or seven inches deep in most spots, even immediately next to the fairway. This year, though, the USGA used a slightly higher cut immediately next to the fairway for four or five feet, then grass only 31 / 4 to 33 / 4 inches deep for five to 10 yards beyond that. The result: Players could hit the ball off-line from the tee, but still recover well enough to make a par or even birdie.

“The rough has not been particularly penal,” 2010 champion Graeme McDowell said. “It’s been set up for scoring. It’s as simple as that.”

One last bit about the setup: In order to fit the modern game, in which equipment allows players to hit the ball farther, Congressional added seven new tees for the Open and stretched the course to 7,574 yards, the second longest in the history of the event. But on any given day of the tournament, the USGA used forward tees on several holes. Sunday, for instance, it played at 7,452 yards. Davis believes that strategy better tests a player’s mind, because he has to decide where to play aggressively and where to back off. The soft conditions, though, made such choices easier.

So Congressional’s Open, whether it was Congressional’s fault or not, became much more like a regular stop on the PGA Tour — and that’s not to everyone’s liking.

“As a former Open champion, it disturbs me that the game has changed,” Strange said. “It’s our national Open, and it’s supposed to be and always has been, as long as I can remember, our toughest test. This was like playing the old Kemper Open. The old Kemper Open was on a harder golf course.”