Jesse Trindall's return from a dislocated shoulder gave Cronulla a needed lift, with Billy Slater describing his display as "Physical courage to go after the game."
Trindall's influence helped the Sharks defeat North Queensland 28-16, although Slater said Cronulla had only "found a little bit of their mojo" and was "wasn't overly convincing."
The former Dally M Medal winner believes Cronulla's roster is strong, but remains unconvinced by its premiership credentials.
"They've got a good team, and they are capable of doing something, but they just aren't showing me enough," he said.
Slater made the assessment while previewing the Roosters match on Nine's The Billy Slater Podcast, warning that familiar shortcomings could reappear.
Cronulla entered the final five rounds with a favourable draw and a top-four place available, but defeats against the Dragons, Raiders, Eels and Storm left them fifth.
A narrow victory over the Titans was their only success during that sequence, costing them a finals double chance.
The Sharks have repeatedly been labelled "flat-track bullies" after beating weaker opponents but failing against contenders.
Slater called Penrith's game against the Roosters a "class above the rest of the finals game on the weekend," saying Cronulla "need to go up a couple of notches."