GSP wrote:Kemba Walker sucks. Hes not much better than Isaiah Thomas for a deep playoff run
Players like him, Dame, Russ (when hes not with Kd), Kyrie (when hes not with Bron) etc show the limits of an undersized guard
Jamal Murray is the probably the floor for a guard that can dominate late in the playoffs. If youre a star Pg and not 6'4 and over 200lbs youre gonna get exposed. Defensively your team will have to cover for u too much and youre much easier to stop on a variety of coverages
Even Steph in the non Kd year benefitted greatly from not playing Jrue/Conley/Bev/Kyrie with all the starting points injured and they wouldve lost in 5 last year if Kd didnt go off in that 1st quarter before he got hurt. We saw how much Steph struggled with Delledova before he was drained and needing Ivs. 
Lowry is one of the rare exceptions but hes gotta be 200lbs and has an ass the size of most centers. You cant really pick on him defensively since hes a pitbull
Weve seen those lumbering bigs from the past era phased out as teams have gotten smaller and their lack of skill/mobility exposed. Think we're gonna see those undersized Pgs start getting phased out too. Teams are gonna start box and oneing and triangle zoning them ALOT more in this era and they better pray they have a Bron/Kd/Ad type of talent
Guys like Murray, Mitchell, Booker, Luka, Herro etc are the new breed. I think Steph is gonna actually really struggle next year with no Kd/Iggy. Teams switch alot more now and i wouldnt be shocked if the Warriors miss the playoffs barring them getting Giannis or a massive trade
Watching undersized guards consistently struggle in the playoffs over the year has made me appreciate Zeke ALOT more. Specially considering the era back then and how paint defense was. Hes generally considered overrated here and he gets a bit too much praise from casuals and certain Nba media but he was just a dog and consistently stepped up in deep playoff runs
Point guards are not getting phased out and you have a very strange definition of undersized. Russell Westbrook is a big point guard. Stephen Curry is not small at all for a point guard. He is 6'3 200 pounds at the very least.
Murray and Mitchell are nowhere near the size of Luka or Booker, and Herro is not a point guard (neither is Booker really). No one looks at someone like Donovan Mitchell and thinks he's large or a mismatch. If anything someone like Mitchell doesn't have ideal size for his position, and is probably looked at something that limits his ceiling a lot.
I don't really see the basis for your conclusion either. Kemba Walker isn't as good as any of those players during the regular season (Murray is the only one, and that's because Murray just was nothing special at all during the RS), so why would he be in the post season. Has nothing to do with his size not working in the late rounds. Box and one would hurt any player running the point, it wouldn't be easier to deal with if Kemba was bigger - it would even hurt Lebron James. Lebron James is not small.
Isiah Thomas had plenty of post seasons where he struggled, he just won championships. That's a winning bias thing - were small guards phased out when he played poorly in the late rounds?
You said Westbrook and Irving's post season success do not count because they played with stars but Murray counts when he plays with Jokic. Jokic is much easier to play with than Durant and James (given Irving's style).
A large reason why Murray is doing well isn't because he is some yolked point guard, it's because he does well against teams with mediocre perimeter defense. He did very well against Utah and then dipped a bit when Conley came back He's doing well against LA who's defense is more concentrated in their bigger players. He did not do all that well against the Clippers where he was against several players who can keep up with him. Not coincidences.