The Australian striker has notched 49 goals since she joined the Blues in January 2020, helping the club to two league titles, two Continental cups, one FA Cup, and a Community Shield.
Arnold signed for the Hammers not long after her compatriot in July 2020 having won the W-League title twice in Australia with Perth Glory and Brisbane Roar.
The 28-year-old was also a member of the Australia national team, alongside Kerr, that won the 2017 Tournament of Nations and Cup of Nations in 2019.
And she gave her take on why her fellow Aussie excels.
"She's obviously got that pace up front but the runs that she makes in behind - they're really smart and she's a really smart footballer and knows where to be at the right time," said Arnold.
"She does pose that threat up front and you need to keep her under control and obviously the rest of their front line as well."
Meanwhile, West Ham are aiming to make a strong end to this campaign as they look to continue their progress in recent seasons
They are still in contention to win the FA Cup and face Ipswich Town in the quarter-finals and they will be looking for a return to Wembley.
In 2019, before Arnold's transfer, West Ham enjoyed a fine run to the final but lost 3-0 to Manchester City.
For the rest of the current campaign, she is keen to take each game as it comes as they hunt for success in the FA Cup and the WSL.
"I think [the season] has gone quite well," she said. "We started out the season dropping a few too many points in the last minutes of a couple of games, so I think progressing from that, we've done quite well.
"I think we are a couple of points away now from getting our best total points in a season.
"We do have quite a hard run of games coming up so it is important for us to stay level at the moment and like I said take it one game at a time and go from there."