The striker, signed from Bristol City last summer was in and out of the side with injuries and only scored a handful of goals - and he blames his lack of fitness in the pre season as a major factor to that.
But now it is a fresh start for Peacock and he knows that he will be a much better player this time out because he will have more time to prepare and get match fit.
He told Footymad: "I have got through pre-season this time ok so far, I have had one bad day with my hamstring but it was only half a day I missed. You have to try your hardest at this stage of the season – sure you are going to get the little niggles but so far things are working out ok for me.
"The Sheffield FC game worked out well, I got a few blisters from my boots but my ankle feels a hell of a lot better than what it has been in the past. It was good for Macca and me to get a positive start.
"The gaffer has set out his stall with what he wants from us and against Sheffield, we did everything right including all the set pieces. At the end of the day it was the first day back and there were a few sloppy mistakes but overall it was a pretty decent performance."
Now Peacock knows it is time to knuckle down, and despite what happened at the end of last season, that success has to be put in the past.
"In my head, Cardiff’s gone now and you can’t look back and think about it," he admitted. "This is a brand new season and we are going to be up against bigger and better teams so we have to up our work rate.
"We can’t look to be contenders but we have to play on a level playing field because if we do well in this league then it gives the gaffer the chance to bring in better players and consolidate because we don’t want to be known as a ‘yo-yo team’ and go straight back down again so we have to stabilise ourselves."
As pessimistic as it sounds, staying in the division is paramount for The Owls although the entire squad knows that they are capable of good things if the attitude is correct.
"Definitely," Peacock states. "You can’t be happy with just staying up and you have to push yourselves as hard as you can. Take Wigan for example: they spent a few seasons in this league and look where they are now – all from working hard.
"We have to stabilise but you also have to go into every single game thinking that you can win – there’s no point by just seeing what will happen, we no longer are in league one where every team we played against deemed it as a cup final, we are now going to be playing against strong teams and everyone will be gunning for everyone."