I don't think you've really watched Lazio in the past two seasons.
SMS literally has to do everything because there is no fucking plan. It's either run to the flanks or push it forward and hope for the best. SMS is literally single handedly controlling the game for Lazio, ensuring they have more attacking than defensive duties.
He's a much bigger player than Pogba was at Juventus. The only differences were the Scudetti and the astronomical difference in wuality between the two midfields. He's no gamble, he's by far the best transfer anyone could hope to land from Serie A.