Didn't Oh Seung-hwan and Lim Chang-yong increase their velocity as they got older?

Both of them were good in the early stages of their KBO careers, but they felt like pitchers throwing in the mid-140s (km/h).
However, both were throwing in the 150s during the latter part of their KBO careers or while playing overseas.
Is this a case where their velocity increased due to age? For Lim Chang-yong, it seems like it might be due to rehabilitation after surgery.
Including Sun Dong-yol, their NPB stats are truly incredible.