Really the Sharks depth isn't terrible. It's not great, but other teams have worse. The top 6 and defense, both of which should be very good, are more worrisome to me. They just seem to be getting the least out of their players on all fronts.
edit: except the pk.
Statistically, the scoring on the lower lines is pathetic. It has been since JT arrived with the short term exception of Mitchell/Pavelski/Wellwood. That has been shown statistically on more than one site. Bottom ten or worse in the league. Their blueline has barely been better for goals. Sure Boyle scores, but the rest of the crew is subpar. The Sharks have been carried by their top 2 lines for a long time.
For a quick rule of thumb, average for the bottom two lines of any team over a season is 60 goals spread over 6 forwards. For good teams, there is usually one bottom 6er with 20 goals. The Sharks have not been close to this standard since Thornton/Ricci/Cheech. For this season, you can use a 1.6 multiplier for projected goal totals over a season and you can go to TSN for projected goals for all of the individual players.
The above is part of why I don't buy the noise about Sheppard, Galiardi, etc. being OK. A true third liner should be good for 30 pts over 82 games. A true fourth liner should be around 10 to 15.