Fred Kaplan presents a reasonably balanced view of Reagan's contribution to the West winning the Cold War, but still gives too much admiring credit to Gorbachev:

The Gorbachev factor—too often overlooked in this week of Reagan-hagiography—was crucial. If Yuri Andropov's kidneys hadn't given out, or if Konstantin Chernenko had lived a few years longer, Reagan's bluster and passion would have come to naught; the Cold War would probably have raged on for years; indeed, Reagan's rhetoric and actions might have aggravated tensions.

. . . .

In the end, Reagan and Gorbachev needed each other. Gorbachev needed to move swiftly if his reforms were to take hold. Reagan exerted the pressure that forced him to move swiftly and offered the rewards that made his foes and skeptics in the Politburo think the cutbacks might be worth it.

Gorbachev wasn't the only decisive presence. If Reagan hadn't been president—if Jimmy Carter or Walter Mondale had defeated him or if Reagan had died and George H.W. Bush taken his place—Gorbachev almost certainly would not have received the push or reinforcement that he needed. Those other politicians would have been too traditional, too cautious, to push such radical proposals (zero nukes and SDI) or to take Gorbachev's radicalism at face value.

Kaplan's assessment is misleading in that it wants to leave the impression that Gorbachev "reformed" the Soviet Union into a democracy.

The historical fact, which was reaffirmed by Gorbachev himself even after the Wall fell, was that he intended his reforms not to end communism, but to save it. Reagan certainly did not intend to "reform" communism. He intended to defeat it. Gorbachev failed. Reagan succeeded. The Soviet Union was not "reformed." It collapsed in defeat.

Reagan "needed" Gorbachev? Well, I guess you could say Sitting Bull needed Custer, too.