You must not have watched Wimbledon in 1989. In the semifinals, Lendl gave Becker all that he wanted and more before the German prevailed in 5 tough sets, 7-5, 6-7, 2-6, 6-4, 6-3. Indeed Lendl might have won the match if not for a rain delay that Becker himself acknowledged allowed him to regroup. Moreover, this was Becker's finest fortnight. The 2 sets dropped to Lendl were the only 2 that he dropped over the course of the tournament, which concluded with Becker beating Stefan Edberg in straight sets, including a 6-0 set. This was the same Edberg who would beat Becker in 1988 and 1990 in the finals.
It was also the Edberg who Lendl beat in the Wimbledon semifinals in 1987, a year in which the Swede won the Australian Open on grass and a year before he would win his first Wimbledon crown. During another year that Edberg would win the Australian Open on grass -- 1983 -- he would have to get past Lendl in the semifinals, 9-7 in the fifth set.
Furthermore, while Lendl never could get past Becker at Wimbledon, including a loss in the 1986 finals, he did crush him, 6-3, 6-2, in the Queen's Club finals in 1990, the second straight year that he would win that title.
There's certainly a case for Roddick being the best bridesmaid ever at Wimbledon, but I would proffer that Roddick does not have two grass court wins as good as Lendl's wins over Edberg and Becker.
I have most of the significant matches from that '89 Wimbledon on tape, and I've watched them enough. That was one match in which Lendl seriously threatened Becker on grass. Maybe I was wrong to insinuate he never
did as much, but that was a real outlier, and even then it felt as though he had a ways to go.
Becker's shot-making and shot-selection on grass trumped Lendl too often. Roddick drew plenty of criticism for looking lost at net, but Ivan barely stood a chance with his arbitrary approach. He went up the middle literally every time off of the serve, giving his rivals passing shots as easy as hitting the ball up the deuce or ad side if he didn't do enough with the first ball. On that day against Becker, he compensated well with a great kicker and line-painting guided volleys for some athletic put-aways. He had to play well outside of himself, and still got dismissed pretty comfortably in the fourth and fifth after Becker found his form.
But yes, we can't forget that Queen's Club match! Haas and Hewitt are also legendary for defeated Fed at Halle. The one thing I'll concede that I overlooked was his defeat of Edberg in '87.
And your point about Roddick's wins is dodgy. The man went 32-3 between '03 and '05 on grass, losing only to Federer. Along the way, he beat names including Rusedski, Dent, Ancic, Hewitt, Agassi, Philippoussis, Karlovic, and Grosjean along the way. Every other decent grass player and/or big-serving, big-hitter type you can think of. Not really his fault there was no Edberg or Becker type to contend with, or that Federer never played Queen's as a tune-up. Nevertheless, his effort against Fed in '09 Wimbledon, to my original point, is far more convincing than any run Lendl ever put together, including that '89 one. And for what it's worth, his run in '04 was just as stellar, and Fed himself has suggested that the rain delay saved him numerous times.