For years I've read that Jayasuriya and Kaluwitharana revolutionized one-day batting at the top of the order with their performances in 1996, until I pulled up the scorecards and saw that Kaluwitharana made a grand total of 73 runs across six innings, with 2 ducks.
His top score of 33 came against Kenya, and he scored a duck in the semi-final against India, and 6 in the final vs Australia. Across the tournament, his scores were 0, 26, 33, 8, 0 and 6.
How did this urban legend of him being some sort of revolutionary LoI champion come about then? Unlike Jayasuriya, he couldn't bowl either.
What an excellent question to bring up OP. It did make me think, and I'll structure my point of view POV answer from the following perspectives.
One, sometimes it's about how a new perspective or approach radicalizes the game, even while the individual who brought about this transformation aren't very successful themselves. This is the bitter sweeet irony of the game we all love.
For example - this is a bit of an OTT comparison - Bosanquet. The man gained immortality as the inventor of the googly. But his career didn't exactly pan out as one would have thought and he's not remembered as a great player. The writer and cricket historian David Frith suggested that the inscription on Bosanquet's grave should have been “He is the worst length bowler in England and yet he is the only bowler the Australians fear.”
In their own way Kaluwitharna and Jayasuriya did indeed bring a new perspective to ODIs- prior to that, in general (exceptions aside) the first ten overs in a 50 over game used to be a sober and sedate affair. What Kalu and Jaya did was to systematically (again, not a one off) and strategically go on an all out assault on the bowling first up. And, hard as it sounds to believe today, as a consistent approach this was new. Go gangbusters in the first 10 overs? Whoa!
Kalu is part of the opening duo that helped bring it about and such he is justifiably remembered for it.
Two, no one says that he was a great bat, or even a very good one. Test and ODI averages of 26 and 22 are pretty poor. But Kalu was successful (not always though) in actually executing this new opening strategy on occasion, if you look outside of the WC. In 1996 after the WC, for example, on the tour to Australia he scored 3 50s at strike rates of close to a 100. Of course his other scores were poor; but the point is he was helping bring a change in thinking.
Three, the impact of Jaya's and his approach to the fans who were watching him cannot easily be quantified. Kris Srikkanth comes to mind as a somewhat comparative example. Srikkanth's averages - just below 30 in Tests and ODI - aren't much kop, even if we inflate these numbers by 5 runs to compare with batsmen today.
But from an Indian fan's perspective you had to watch the guy. At a time when our batting approach up top was slow, steady and frankly dull, here comes a guy who goes wham! bam! at the fastest bowlers going. Like the meme driven honey badger, Srikkanth didn't give a $%$% either. And his successes, while few, were eternally sweet and ever fresh in fans' minds.
And so for Kalu.
Four, here's what actually happened in that WC. Sri Lanka tore India a new one- I was watching it and I can never forget that assault by Jaya. But as I found on the net, Jaya had an average of19.53 from 98 ODIs before the 1996 WC. Kalu was closer to 10! But Sri Lanka has this strategy and in that WC that strategy worked. You can say what if they hadn't won, but that's not valid. They won, and that's it.
Jaya went on to execute brilliantly in his career, and also discovered a higher ceiling. While Kalu was left behind in terms of numbers and accomplishment, but his opening combination with Jaya (till 2004, which says something) gives him a certain cachet in the game. I doubt anyone considers him a legend, but he has his minor place in cricket history, and justifiably so.