But a try from Treviso fly-half Sam Christie spark brief hopes of a comeback as the home side failed to start the second half as they had the first.
"I thought the first half we played really well, we kept our shape nicely and we made sure we kept our structure and not allow Treviso to get broken field ball," said Doak.
"And the boys did that well and the pressure we put on them resulted in the two yellow cards and it is a credit to the guys.
"At half time you want them to kick on and the start of the second half didn't go as planned and it becomes a little bit disjointed and you allow then back in the game.
"We have played against Treviso many times and been in front and allowed them back into the game and they put us under a little bit of pressure but I couldn't be any happier with a bonus-point win."
"It is a bit of a mental game when you have the bonus point by half-time, you hope you can score early doors and really put them to bed but they got those points on the board and we lost a bit of shape.
"We lost a bit of our way but we got it back again and finished it off with a few more tries."
To buy tickets for the GUINNESS PRO12 Grand Final click here. Also follow us on Facebook, join the conversation on Twitter, sign up to our YouTube channel for extensive match highlights and sign up for our newsletter for regular updates on the GUINNESS PRO12.
63x46.png){kind=logo}