Interesting comment by Paul Wallace on props

He said that it's possible that a prop would be able to switch from Tighthead to Loosehead but highly unlikely that it would work the other way round. 
It kind of goes to show, hopefully the Sharks will end Thomas Du Toit's experiment at Tighthead and put him back at Loosehead where he excels. 
This opinion could also apply to Coenie and Nyakane who was played at Tighthead by the Bulls, Trevor is a really good Loosehead.

Perhaps a bit tall for tighthead.  

Coenie has been good at tighthead this year as has Nyakane.
Thomas du Toit needs to establish himself as a loose head before they contemplate a change. 
The new Sharks tighthead.....Engelbrecht had an impressive debut for them....the lad is huge.
Thomas came on as a loose head which was good to see.

Nyakane is a much better Loosehead. 
I'll concede Coenie has got to stay at Tighthead just because his neck isn't strong enough for Loosehead, but purely on ability in each position Coenie was far better in the latter.

 Disagree on both counts....Coenie and Trevor are equally good at 1 and 3.  There is more pressure on the neck at 3 than 1 

 The reason why Coenie made the switch from Loosehead to Tighthead was because it would lessen the risk of injury to his neck.

No it was not.....at 3 you have the pressure of the 2 and 1 exerting pressure on your neck, at 1 you only have the 3 exerting pressure on your neck

I'm not sure about the technicalities, but I also recall Os discussing the switch to tighthead to preserve Coenie's neck.