And the ex-Stags keeper said learning from Cox, as well as Paul Hart at Forest and Steve Chettle at Ilkeston Town, has helped him in his own successful fledgling managerial career.
Badly-timed injuries cost Deakin his chance to shine as a keeper in the EFL after once again linking up with Cox at Stags in 2013/14.
Deakin had enjoyed two promotions with Cox at Eastwood Town and said: “I still call Paul Cox the gaffer now.
“I worked with him for probably eight years of my career – a big chunk of it and he was very good at getting the best out of players.
“He understood what it required at the level of football he was playing at to get results.
“The Conference is very difficult to get out of – it's a very tough league. But he managed to do that.
“Paul Cox and Paul Hart were the two biggest influences on my career going into management and coaching.”
Deakin was handed a dream chance to play in the EFL and link up once again with Cox in 2013. But the dream fizzled out for him as an injury-hit career got no better.
“Injuries continued to plague me at Mansfield and I think I had a torn shoulder and a torn quad muscle – it never really worked out as well as I wanted it to,” he said.
“I went in as No.2 to Alan Marriott but really struggled with the injuries. The mind wanted to but the body wasn't working as well as it should have done. I never really got going.
“When Alan was injured, I played a game as a fitness test away at Hartlepool but didn't come through it and it was emergency loan time for the club.
“The stars didn't align for me while I was here but I still had a great time. It was fantastic.
“It was a good experience but I still look back on it and wish I had managed to stay a bit fitter and play more games for the club and be there a bit longer.”
Deakin is now the Stags' new commercial executive and said: “It's funny how things change and you end up coming back in a different capacity.
“It's interesting as you see how a football club works from the other side.
“As a player you just turn up with your boots and train and play and don't see the hard work that goes on behind the scenes.”
Deakin came through Forest's youth system and said: “You take bits from different managers you work with over the years and, for me, probably Paul Hart at Forest, and Paul Cox were the two that I took the most from.
“Paul Hart put me into the Forest first team squad at 16 - out of necessity really with a similar kind of crisis to Mansfield, this season. But you have to take your chance. He wasn't bothered about putting young players in.”
After Forest, Deakin enjoyed an adventure playing for Colorado Rapids in the USA.
“A team came in for me and it was a bit of a whirlwind and within probably a week and a half I was on a flight out to Colorado,” he said. “I spent a couple of years out there.
“But I suffered with injuries there, which was the starting point of a chain of events where I struggled with injuries throughout my career.
“Then my mum took ill with cancer and I did not deal with that very well as a young man. I was quite close to my mum – she brought me up on her own.
“So I came back and came out of football for a little while. But she then had a conversation with me and said she wanted me to play again.
“So I signed for Paul Cox and was with him for most of my career after that.
“Obviously I did very well at Eastwood with him and then the phone call came and he said he wanted me to come and play for him at Mansfield Town along with several other players he'd worked with at Eastwood.”Any hopes Deakin had of establishing his claims for the following season were destroyed when Stags' budget was reportedly cut by half and he found himself on a long list of players shown the door, ending up non-league at Heanor Town.
“That happens in football sometimes and you understand as a player it can happen at any point,” he said.
“Sometimes a rebuilding process comes into it. You looks where we are now and the playing staff and the manager we've got and hopefully now we can push on as I believe Nigel Clough is the right man and we have some really good players.
“Sometimes it needs a clear-out to freshen things up and make things change and that's football. It's never personal. That's what happened that season when a lot of us left. To be fair a lot of us were getting old as well.
“I think I was almost 30 at Mansfield, which isn't old in goalkeeping terms, but I was suffering from injuries so I kind of knew where my situation was. It's the harsh reality of football sometimes.”
Deakin loved working day to day with Alan Marriott over that one season.
“Maz was great – a really good keeper. We worked well together in training,” he said.
“He was a proper professional and had the longevity, and he was a great guy as well with a great personality.
“I wanted to play, but my job was also supporting your team mate and making sure he's ready to go. We had that support mechanism in place and he is a club legend.
“He even scored a goal. I remember it well. We used to joke about it all the time as I had scored one in my career too and there are not many keepers out there who've scored a goal, let along two at the same club.”
Deakin's goal came while on loan at Buxton from Eastwood where he lined up a free kick 20 yards inside his own half, stepped up and with a swing of his right foot managed to find the back of the net!
Deakin spent 2016/17 managing Kimberley MW and the season after went to Ilkeston Town as player/assistant manager to Steve Chettle.
“I learned quite a lot in a short space of time at Ilkeston. I spent a year and half with Steve Chettle before he went to Notts County at the back end of the last season,” said Deakin.
“But we won two promotions there. I played in the first year because he asked me to. I didn't really want to. But we managed to get promoted.
“The second season we won the league for the first time in 20 years for Ilkeston.
“They had suffered a torrid time with ownership issues and so on, it was nice to give the fans something to cheer about.
“I learned a lot from Chets. He was very calm, a very good coach and tactically astute. He had played at the highest level and you want to learn off people like that.
“I was soaking it all up with him. We worked well together as I am quite a passionate man when it comes to football and Chets is quite calm, so the yin and yang worked well together and they continue to thrive now after we moved on.
“The new owners have come in and the new coaching staff and it's brilliant to see them going from strength to strength.”