A Vlad with speed-ups cast on him is no different than a Juggernaut with them. Not really an issue if a team is literally being built around a champion.
Nobody would say a "Protect the Kog" comp makes Kog'Maw a balance issue.
Cautious buffs? He's the lowest win-rate top-laner now. He could use some substantial buffs.
#The only thing they should be cautious about is anything that affects tank builds:
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Base damage
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HP->AP ratio on passive
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HP ratio on Q
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HP ratio on W
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HP ratio on E
Anything else is fair game and very, very likely would not push Vlad too far. There's very little Riot could do with minor balance adjustments that would push him up more than 7% in win-rate, which would only barely put him under 50% win rate.
However, competitive would pick him up the moment he's able to even barely function solely due to what his ult offers and how safe he can be.
His ult is the core of every one of his issues because his only issues are the tank build and the fact that Riot doesn't like seeing him as a competitive staple.