Even before his first full day as Lakers president of basketball operations ended, Magic Johnson pulled off a trade that will help the Lakers in what figures to be a long climb back to respectability.

Journeyman guard Lou Williams to the Houston Rockets for journeyman forward Corey Brewer and a Rockets first-round draft pick.

Some might say: “Lou Williams was the Lakers’ leading scorer!” But that matters little, if at all.

Four reasons why this was a fine first trade by Magic:

–It diminishes the team slightly for the remainder of this season. This is good because these Lakers have little-to-no chance of reaching the playoffs, and a weaker Lakers over their final 24 games improves their chances of finishing in the bottom three of the NBA standings — and having a shot at keeping their top pick in what is considered a strong 2017 draft.

The Philadelphia 76ers get the Lakers’ first-round pick (an unpleasant consequence of the Steve Nash trade, a hundred years ago) unless the Lakers are in the top three of the draft. At the moment, they have the third-worst record and thus have a 46.9 percent chance of getting one of the Nos. 1-2-or-3 picks in the lottery — and keeping it. If they can sink to No. 2 in the standings, below Phoenix (only a half-game worse, at the moment), the Lakers’ chances of getting a top-three pick move up to 55.8 percent. They cannot aspire to The Worst Record, not with the Nets at 9-47 to the Lakers’ 19-39, but they can dream of getting the second or third selection.

(Lonzo Ball, anyone?)

If the Lakers move up a spot, to the fourth-worst record … that draft pick automatically goes to the Sixers. (And at least one Sixers blogger has suggested the Lakers are “tanking” — and that was before the Williams trade.)

–Leading scorer or not, Lou Williams was not going to make the Lakers into a playoffs team. The man is 30, has been coming off the bench, and his 18.6 ppg is an outlier, in his career. The Lakers can give his minutes to one of their young back-court guys. Meanwhile, Corey Brewer fills a bit of a need. He can’t score, but he plays defense and, at 30, can play the older statesman role. His contract has another year on it, for essentially the same money ($7 million and change) Williams was getting, so no outlay there.

–The Lakers gain a first-round pick from the Rockets. The pick is believed to be for this season, but that has not been finalized, as of this writing. It would not be a high pick — probably in the 25-28 range of the first round. But any first-round pick is useful. The idea of stocking up on young talent is Step 1 in moving the team forward.

–The deal was a little sly/crafty. Subtle, in a way you would not expect from a man with no front-office experience. Look again at the three reasons listed (above). Makes current Lakers team a bit weaker; gives up a guy who was never going to be a star, let alone a superstar; gives the Lakers a first-round pick — all of which tend to blur out, a bit, the “tanking” allegations.

Not bad for Day 1.