In the same wikipedia:
Navantia engineers had
miscalculated the weight of the submarines by some 100 t (98 long tons; 110 short tons) of the total 2000 tonne mass of the submarines, more than enough
to sink the submarines if not fixed. As of 2013 Navantia announced the issue would delay the delivery of the first submarine to the Spanish Navy until at least 2017. That date proved to be optimistic. Lengthening the submarine created additional
buoyancy.
Navantia signed on the US company General Dynamics Electric Boat to help solve the excess weight design issue. In September 2014, the overweight issue was reported to have been resolved in design changes and the construction work to be ready to resume in late October 2014. In November 2014, Navantia again reported having completed the redesign work to address the problem of overweight. In all, the hull would be
lengthened by 10 metres (33 ft), and the displacement increased by 100 tons.
It's true that they've changed the diameter a little, but between adding a section for the AIP (as we're going to do on the Scorpene) and 10 metres for calculation errors, that's a change in length which also contributes to the increase in size.