Great question which would deserve very comprehensive answer. I will try it to put it to the nutshell.
I have not watched Plotnikov so much, but he is 25 years old regular KHLer playing in the KHL top team which could compete with some NHL clubs. On the other hand Simon is just 20 and he smth. like PROJECT of czech hockey. He is basically the example CZ association shows how they want it to do with young players. He played for Sparta Prague but had not guaranteed top 6 spot so he moved to Pilsen. They put him to the first line and gave him a time. He was pretty much out of shape in the beginning of the season but they still kept him in the first line just because of his potential and room for grow. They let him play for Cz national team in Euro hockey tour even if his performance was poor meanwhile, reason was - int. games help him to grow. That factors logically signaficantly improved his play and he also made a big step up compare to last season. And it also lead to his nomination to WC team (as a 4th liner,he played top 6 just in one match, if I remember clear, nevertheless that 4th line was great all the tourney) He is still making progress so I am not sure if he is complete player like Plotnikov, and he is also smaller. Thats the reason why he will start in AHL if he doesnt outshine everybody in camp imo.....
Problem with the system above is for the league czech clubs imo. Pilsen gave him big chance to develope. However they did not make it to Playoff and he is leaving after one year so he is not bringing it back and they have to find another 1st line center....Which lead me to quality of both leagues. KHL is definetely much higher quality league than CZ extraliga (KHL pretty much hire best european fins,swedes,czechs etc.) On the other hand I dont see any cz player,except KOvar, staying in KHL and become better and better player. Best czech clubs are also able to beat some KHL clubs (at least in preseason game).Still staying in cz league is generally considered as a risk among young cz players with NHL potential. I dont see the big reason for it as they get more and more this "personal" treatment from clubs and national team. Staying one more year in CZ would still help Simon IMO no matter of CZ league quality (its actually not that bad). And clubs would finally benefit from this system. However stats are against my opinion. Recently there was just Hertl going straight from CZ league to NHL and than Michalek before him somewhen around 2004. So because guys like Simon are not that talented, grow later (because cz junior league does not provide that quality as NA junior leagues)and dont know the culture, NHL teams still want them behind sea pretty much ASAP and let him play in AHL even if they would be probably able to play 4th line in NHL immediately. This is where factor of KHL quality helps - plying with guys like Kovalchuk, Radulov etc. make NHL bosses probably more calm than playing with maybe skilled but basically no name guys in CZ
So rule is clear now: KHL -> NHL; CZ ->AHL->NHL unfortunately
Sure factor of diff. style of hockey must be mentioned..... Hope I wrote it understandable way
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