"But if he helps the Red Sox win the World Series, no one will worry very much about what the team gave up for him."
This is the key line of the article.
Recall another blockbuster, almost 20 years ago, when the Red Sox traded another guy rated by some as the top MLB prospect: Hanley Ramirez. Look at his first half decade as a Florida Marlin: Rookie of the Year, three All-Star selections, two Silver Sluggers, MVP finishes of 2nd-10th-11th, a batting crown, a runs-scored crown, and 162-game averages of 5.6 WAR, 200 hits, 120 runs, 74 XBH, 42 stolen bases, .313 BA, .909 OPS. Yikes.
(unfortunately, in his last nine years, he turned into Hanley-being-Hanley, and did not make Cooperstown).
But nobody ever complained about losing HR, after Josh Beckett was the best pitcher on the planet in the '07 postseason, and Mike Lowell won World Series MVP.