In 2007, Luol averaged 18.8ppg on .560 TS%.  Take out that season, and his career TS% is .515.  We're all hoping for a resurgent season.

Here's something I haven't noticed before, though.  His positional splits from that season (per 48 minutes):

SF: 22.9pts, .502 eFG%, 5.4 FTA, .543 TS%
PF: 29.6pts, .594 eFG%, 6.8 FTA, .633 TS%

Oddly enough, for as well as Deng played at PF in 2007, his minutes at PF have dipped since.  Approximate minutes played at PF since '07:

2007: 518 minutes, 17% of his playing time
2008: 161 minutes, 8% of his playing time
2009: 162 minutes, 10% of his playing time

Overall splits from 2007-2009, again per 48 minutes:

SF: 22.5pts, 5.5 fta, 8.6reb, 3.3ast, 2.5to, .532 TS%
PF: 26.8pts, 6.5 fta, 10.6reb, 2.3ast, 2.1to, .597 TS%

The low TS% at SF seems to correlate to his jumpshot percentages over the past three seasons:

2007: 42.6 eFG%, 61% of FGA were jumpshots
2008: 40.6 eFG%, 61% of FGA were jumpshots
2009: 38.1 eFG%, 66% of FGA were jumpshots

Luol's jumpshot is partly to blame, and I expect it to top 40% again this year now that he's healthy.  But the data seems to suggest that Luol's return to 2007 efficiency is also dependent upon playing more PF.  With the news that James Johnson is practicing exclusively at SF, I'd say the chances are good.