Bill Buckner was a VERY good baseball player. He was a career .289 hitter (with over 2,700 career hits) who won the NL batting title in 1980 with a .324 batting average. He struck out just 18 times that season.
Over his 8 seasons with the Cubs, his batting average was .300. He is on the relatively short list of guys who played in the Majors in 4 decades (1969 to 1990).
Correct, and I'll add two other notes to this that REAL baseball fans will already know about Buckner.
1. His best position was left field; he became a full-time first baseman only after a staph infection ruined his ankle. He was never the same, really, and was the first big leaguer to wear high top cleats to try to take some of the stress away from his ankles. Watching him run was painful for most of his career, but he could HIT!
2. The REAL error in Game 6 was by the Red Sox manager, John McNamara, who had been using Dave Stapleton as a late-inning defensive replacement for Buckner much of the season; inexplicably, he did not do that in the bottom of the 10th inning with the lead. It was an epic fail by McNamara, one of several in that series, with most of the others revolving around odd pitching strategies.
It's always bothered me that Buckner is remembered the way that he is, rather that for a long, productive career played mostly on one good leg. He's currently 66th on the career base hit list, and some of the names below him are pretty stunning; Dave Parker, Billy Williams, Ted Williams, Jimmie Foxx, Vlad Guerrero, Ernie Banks, Joe Morgan, Jim Rice, Mickey Mantle, Joe DiMaggio, and so on. There are TWO active players with more hits; Pujols and Miguel Cabrera, and Cabrera just passed Buckner this season. The guys that are ahead of him on the career hit list are almost all in the Hall of Fame; of the 15 that are not in the Hall, 5 are not yet eligible, 3 are steroid guys, and one is named Pete Rose. On top of THAT, there are only 35 men that have played more seasons of MLB than Buckner, and nearly half of those were pitchers.
By any measure, Buckner's career was exceptional. That he is remembered for that play is much more a commentary on the media and fans than anything else.