The 19-year-old became the latest player to leave St Mary's Stadium in the off-season, following the likes of Rickie Lambert, Adam Lallana, Luke Shaw and Dejan Lovren, joining Arsenal on a long-term contract for an undisclosed fee on Monday.
The England Under-19 international only made his first-team debut for Southampton on the opening day of the 2013-14 campaign and the defender spoke of how quickly things have moved on for him since that 1-0 win at West Brom in August.
"It has been a bit of a whirlwind for me," he told Arsenal Player.
"I have managed to keep my feet on the ground and worked hard but it has been quite a mad [11] months!
"From under-21s to first-team football is such a big step. I think it is more mentally than physically challenging, and over the Christmas period as well it is very tough.
"I loved [my first season]. Every experience I got was such a good feeling to go out there and play against players of such quality. I just want to keep doing it more and more.
"I was a midfielder about a year and a half ago for [Southampton] under-21s. I saw an opportunity in the first team at right-back and thought that for my progress it would be best to move there.
"I used everything I learnt in midfield like first touch, scanning and all that and brought it into [playing as a] right-back.
"I learnt how to play there with the under-21s and went through each game afterwards with the coaches and worked on little bits and it just went from there."
