It is, although it's likely that his speech will never be quite as fluid as he would like.
The brain is pretty remarkable in terms of its plasticity (meaning its ability to rewire itself over time)
Pekka will have a lot of work ahead of him though- speech, although it seems simple, actually requires an immense amount of muscular coordination, meaning that it requires an immense amount of coordinated neural activity. Pekka's brain is still in the process of rewiring itself, and the one of the only ways to ensure that the rewiring goes correctly (meaning it rewires to function normally or close to normally) is to keep working through the speech rehabilitation and generate stimuli. In terms of a lot of neural pathways, you either 'use it or lose it'.
I've actually had a very similar TBI, and have a B.S. in Cognitive Neuroscience. TBI's kinda suck.
