Tons are senseless metric to see impact of lower order batsman in long careers because it happen so rarely.
As far as two batsmen in question.
Jadeja in wins: 20 times he chipped in with 50+ scores. It means every 2.5 test wins, Jadeja was there with 50+ contribution in test match to help his team win.
IK in wins: 5 times in his career he chipped in with 50+ scores in wins. That means, every 5th test wins for Pakistan IK contributed with 50+ scores.
It's even more lopsided away, IK has just 1 50+ scores in win away while being part of team with 9 away wins. Jadeja has 7 50+ scores while being part of team with 14 away wins. I won't focus in exact number , but rate tells me that more often you score 50+ while batting lower, you will help your team consistently.
4 tons vs 5 tons in 80-90 tests, not going to tell much lower order batsman. Differences in most cases are not going to be meaningful in long career.
15 vs 30 fifty plus scores , tells a lot more about lower order batsman in 80-90 tests. Difference in most case is meanigful in long career.
Ignoring 15 vs 30 fifty plus and focusing on 4 tons vs 5 tons is just illogical for lower order batsman. Yes, I am aware of fans not counting anyone as all rounder till they get some tons, but two players in comaprison have 5-6 tons so non-issue.
In short, as a lower order batsman you have a far more chance/instances/oppurtunities to influence the game with 50+ contribution than 100+ contribution. It's true with Jadeja and IK situation. It will be true in pretty much all situations.