Al Oliver had the highest batting average of all the Rookie of the Year candidates in 1969. He also had more homers, RBIs and stolen bases than NL R.O.Y. Ted Sizemore. With 20/20 hindsight it is obvious that he would go on to have the most productive career of all the R.O.Y. candidates. He was a career .303 hittter, a 7 time All Star and a 3 time Silver Slugger. In 1982 he led the league in hitting, RBIs and extra base hits. He came in 3rd in MVP voting. Although he never won the MVP he received MVP votes 10 of his 18 years in the Majors.
It's easy to sit at a computer and second guess sports writers' decisions 43 years in the past. Lou Piniella and Ted Sizemore both had solid rookie seasons a went on to have productive MLB careers. But for argument's sake I could definitely see the NL Rookie of the Year award going to Oliver who crushed Sizemore in every offensive stat. And the AL R.O.Y. going to Carlos May who was the only R.O.Y. candidate selected to the 1969 All Star Team. He also had better numbers than Piniella despite missing the last month and a half of the season.
This is just one of the ways the 1969 R.O.Y. class could have looked. In the A.L. you also had Mike Nagy who went 12-2 for the Red Sox and Ken Tatum who had 22 save and a 1.36 ERA for the Angels. Tatum also received 2 MVP votes to Piniella's 1.
In the N.L. Coco Laboy batted only .258 but had more homers and RBIs than either of the R.O.Y. winners. Larry Hisle had 20 homers and 18 stolen bases for the Phillies. Bob Didier of the Braves also received a couple votes but I can't figure out why. He hit only .256 with no homers and defensively, he led the league in passed balls and was 5th in allowing stolen bases.