Well, they were also approx figures anyway, and in any event are effected to a great deal by external factors like water temp, salinity, windspeed etc.
The point is more broad - a huge comparative power deficiency for a ship of overall same size.
Why is it so? I'd say it's all about doctrine. The way the PLAN wants to use its FFGs (screening task forces, point air defence & ASW), they don't require a lot of motive power. The ones the DO require all that power would be the CODAG/CODOG-equipped DDGs like 052C/D which would be the main surface/anti-air combatants in any task force and therefore the main sea-control assets.
But the problem only becomes pronounced when these FFGs are being used as flagships/main surface combatants by likes of Pak Navy, and going up against vessels that would be enjoying a significant power advantage in surface combat.
This is not what the 054A class was designed for.
It's not just about speed - but about how quickly you can attain that speed, how long can maintain that speed etc etc That's where the power advantage comes in.
The hull refinements can help to make the ship more fuel-efficient, but effect is very marginal in the broader picture. The disparity here is brought on by doctrinal differences - not necessarily design ones.