The New York Red Bulls mostly owe their unlikely run to the top of the Eastern Conference - and a shot at the 2017-18 CONCACAF Champions League - to a 15-game unbeaten streak in MLS. But they also owe a small piece of it to D.C. United.

The old rival has done RBNY some favors recently: beating the FCs of Toronto and NYC in back-to-back weeks to take the heat out of the race for the Eastern Conference. The Red Bulls have won their last three league games; DC has won its last four: together, they cleared a path for RBNY to (is it necessary to keep writing "effectively"? Is anyone believing NYCFC will turn around a 13-goal deficit in one round of matches?) clinch the East.

One man has been instrumental in the recent success of both RBNY and DC: Lloyd Sam.

When Sam was traded to DCU in early July, it was a surprise for two reasons: he was a regular starter and proven attacking contributor for the team; it is generally considered a bad idea to trade away key players to rival teams. But RBNY's wheeler-dealer-in-chief, Ali Curtis, has an almost unerring instinct for a good trade, and hindsight (not for the first time) has validated his decision.

It seems a long time ago now, but back at the beginning of July, the Red Bulls were in a slump. The team's terrible start to the season - six games lost out of seven - had been countered by a bracing run of six wins in eight games, and then the team stumbled again. A loss to Real Salt Lake was followed by a draw in Columbus, Philly bouncing RBNY out of US Open Cup, and a loss to NYC FC. A four-game winless streak saw the team teetering on the edge of plummeting back to the depths it had endured earlier in the year.

We may never know how long the Red Bulls were plotting a change, but the move seemed to come quickly, even hastily. A report from Big Apple Soccer cushioned the blow: we learned Sam was on the trading block on July 6. On July 7, to his surprise as well as that of fans and teammates, he was gone to DC.

The Red Bulls haven't lost a game since.

That is not to suggest that Sam was the reason for RBNY's early or mid-season struggles. While Sam's scoring stats were down (one goal and four assists in 16 league appearances) from his usual standard, his primary replacement - Alex Muyl - has not offered a dramatic improvement on that front. Muyl has one goal and six assists from 26 league appearances this season. It might simply be the case that, this season, the role Jesse Marsch expects of the player in his formation's nominal right wing slot just isn't conducive to gaudy attacking stats.

The thesis that Sam had lost a step and lost the edge that made him effective in MLS doesn't hold when you consider what he's done at DC. Since arriving at RFK Stadium, Sam has made 13 league appearances and provided three goals and six assists. Pertinently, he has been on the score sheet for each of DC's last four games: all wins, two over RBNY's erstwhile rivals for the Conference title.

Lloyd Sam was supposed to be a major attacking threat to RBNY's challengers this season. And he has been, but he's posed that threat most effectively in a DC shirt. And the Red Bulls have found their best run of form without him.

With Sam on board and a few other tweaks, DC has charged into the playoffs as one of the hottest teams in the league. Without Sam, RBNY has been the best team in the Eastern Conference.

The Sam trade stands out as an unusual case of addition by subtraction. When the deal was done, RBNY didn't seem to get very much in return for one of its all-time best attacking players: just some allocation money. And the team's explanation of its reason for trading Sam was incoherent, or at least Jesse Marsch's attempt to explain wasn't great:

It was done with the future in mind, but also with the present. It wasn’t done specifically for a player move, right now. Let me make that clear. There’s some potential for some player moves in this transfer window. This was done on a lot of different levels to strengthen our club. The allocation helps with flexibility for the roster, it helps for flexibility for future moves. We also think there’s potential for guys that are here to step up and fill the void in a major way.

OK, Jesse.

But at this moment in time that elaborately phrased non-explanation seems prophetic. The team did eventually make some moves in the transfer window: about a month after Sam was moved on, Daniel Royer and Omer Damari landed on the roster.

Both have shown promise, but both have also been injured recently. To date, they have provided one goal and one assist (both from Royer) in nine league appearances combined. Hardly numbers Sam wasn't providing.

So the Red Bulls didn't get a significant attacking boost to the squad from the new faces. Not yet, anyway.

And those already on the roster who stepped up to replace Sam have not provided more goals or assists than he was bringing to the team. Instead, it is Sam who has got back into the sort of form that he used to show for RBNY and that had been assumed to make him too valuable to trade - and he has found that form for another team.

He was traded for nothing in particular. But the Red Bulls have got their act together, and Sam has helped DC clear RBNY's path to the Eastern Conference title.

The success of the trade will likely be judged on the playoffs, the longer-term performance of Daniel Royer, and whether or not Sam stays with DC and continues to contribute significantly for another season or two. Trades are constantly re-evaluated as the context around them changes.

But the Sam trade has already been successful. RBNY was dipping out of form and back into trouble, and offloading Sam - for reasons other than goals and assists from him or his replacements - helped correct the team's course. There will be great consternation if the old Red Bulls favorite makes a winning contribution to a DC victory over RBNY in this year's playoffs. But Sam wasn't shipped out to strengthen the Red Bulls for the post-season; he was moved on as part of the team's effort to ensure it made the playoffs at all.

Sam's form for DCU has pushed the Red Bulls' closest rivals in the standings down at just the right time. The result is RBNY's present status: Eastern Conference champion for the second year in a row; CCL berth secured for the second year in a row; a regular-season game to do with (pretty much) as the team pleases, before the work of focusing on the post-season begins.

The playoffs are a lottery. A slalom that can be undone by one moment of bad luck, or one wrong decision. Sometimes the best team wins, sometimes it doesn't. But RBNY heads into the post-season from a position of strength, qualified as best in the East with a game to spare. The last game of the regular season, against Philly, can be mailed in if it suits the team's need to rest key players for the post-season. Such a luxury, and lofty position, did not seem at all likely at the beginning of July.

The season wasn't supposed to work out this way: with Sam in the black and red of DCU. And yet it also was, in the sense that Sam was supposed to spend the year as an irrepressible creative attacking force, helping to scatter RBNY's rivals.

Not for the first time, but probably for the last: thank you, Lloyd Sam.