Doubt on hydrolysis

I mean to say that how can OH- replace sec butoxide anion ...when OH- is weaker base than sec butoxide??

RO is a better leaving group than OH , and hence Oh replaces it

But OR- is more basic than OH-....and less basic is the grp... better is the leaving grp...
Isn't it correct??

Please help me here..I am very confused and stuck at this...anyone who may extent his help is welcome..