Panucci, Mexes, Chivu, Mancini, Totti, De Rossi, Taddei, Perrotta, Aquillani, Dacourt, Montella...... he inherited these guys when he joined Roma. In his first season he didn't make it even in top 4 but Calciopoli saved him. In his second season he was second ONLY because all the others, apart from Inter, were relegated or had many points deducted.
His third season was the only successful one, but no way Ranieri had a better team than Spalletti last year(and yes, it was mostly due to the players Spalletti already had in Roma when he joined the team). Nope, not only that our team wasn't MUCH better as you put it, but it wasn't even better.
This year though, it was a disaster for Roma.
But yes, it's hard to say that Ranieri is better than Spalletti. What isn't hard to say though is that Spalletti's team easily falls under pressure and is losing it way too often. Those are characteristics i would never want in my team.
Ranieri should GTFO ASAP, but i see no real improvement if the baldy replaces him.