arsenal legend thierry henry says ` wenger has to strengthen ' the gunners .
however the progress of hector bellerin , francis coquelin and nacho monreal has been significant this season .
to come second in the premier league and defend the fa cup can be seen as progress .
but the arsenal manager has two years on what could be his final contract .
alexis sanchez says arsenal must challenge for the title next season .
thierry henry : arsenal ca n't win title with olivier giroud in attack .