10% speed aura with no speed boosters with 171 and 181 base speed on your nukers with that level of attack on Kael and crit damage on both of them? You sure you didn't move some items around because I have an extremely hard time believing that with the setup you just linked, you are winning in silver. It took me getting my High Khatun to 235 base to even go first frequently enough to get into silver. It took a second speed booster to get my Kael (who was higher than either of your champs) to go fast enough to be able to nuke. Your defense is nonexist so you aren't surving strikes. Let's just say that Plarium is giving you very different opponents than most of us faced if you can win anything at that level. I am also flabberghasted that your team power is that high with such low stats.
The difference would be his player power - as trevor pointed out above, it was already obvious from Frost's description of his experiences, losing his account and starting over with a strong focus on arena and a small team of champions, that he would profit strongly from the matchmaking system. Presumably you have a significantly higher player power than his 233k because you have a wider roster, so you get far harder opponents.
So what he says makes sense as far as it goes, but he's leaving out the part where his approach only works if you are super focused on arena from day one - which actual new players are unlikely to do, as they'd generally want to try all parts of the game.