While this will not be quite the X's and O's post that Steve's was, this is mainly looking at how balanced an offense fans can expect to see under Trestman.
Obviously, Trestman is mainly known for his work with quarterbacks, and that's all fine and good. Jay Cutler needs all the help he can get and a new system with a known QB guru to with could easily get him on track for a monster season. However, the Bears also have some pretty darn good running backs in Matt Forte and Michael Bush.
Now everyone understands the concepts of the West Coast Offense. Trestman, in the Bill Walsh-school of WCO uses a short, quick passing game to set up deeper passing plays and longer run plays than the old-school basic "run-first" offense. Basically, a typical Walsh-esque WCO would be expected to pass 65%-80% of the time. However, since they are short, quick passes they have a high percentage-completion rate and not as much balance is needed.
That said then, don't expect Trestman to have all sorts of run/pass balance.
Here is a breakdown of Trestman's NFL offenses and their offensive balance:
1989 Cleveland Browns
Rush Attempts: 448
Pass Attempts: 529
Ratio: 54.1/45.9% Pass/run
1995 San Francisco 49ers
Rush Attempts: 415
Pass Attempts: 644
Ratio: 60.8/39.2 pass/run
Rush Attempts: 454
Pass Attempts: 550
Ratio: 54.8/45.2 pass/run
1998 Arizona Cardinals
Rush Attempts: 450
Pass Attempts: 552
Ratio: 55.1/44.9 pass/run
Rush Attempts: 396
Pass Attempts: 558
Rush Attempts: 343
Pass Attempts: 554
Ratio: 61.8/38.2 pass/run
2002 Oakland Raiders
Rush Attempts: 414
Pass Attempts: 619
Ratio: 59.9/40.1 pass/run
Rush Attempts: 423
Pass Attempts: 521
Ratio: 55.2/44.8 pass/run
It's pretty simple then; look for the Bears to carry a ratio anywhere between 55/45 and 60/40. That is actually pretty balanced when you think about it because very rarely are teams right at the 50/50 mark and in today's pass-first league, the balance is continuing to shift up towards the 60/40 mark and beyond.
Here are the pass/run ratios for the last five Bears teams with the offensive coordinator in parentheses:
2012: 50.8/49.2 (Tice)
2011: 50.9/49.1 (Martz)
2010: 53/47 (Martz)
2009: 60.1/39.9 (Turner)
2008: 54.9/45.1 (Turner)
So expect to see more of a Ron Turner balance, but Trestman is supposed to be a much better play-caller.
Furthermore, Trestman utilizes his running backs as receivers, meaning that Forte could see 18 carries but catch another 5-7 passes per game. Trestman has had only one 1,000 yard running back in his offense; Adrian Murrell in 1998 with the Cardinals. He had 1,042 yards. Trestman's fullback in that offense, Larry Centers, caught 69 passes that year, to Murrell's 18.
Here is a quick rundown of the lead RBs Trestman has had with their rush yards, yards-per-carry and reception totals:
Eric Metcalf: 187 attempts, 633 yards, 3.4 yards-per-carry and 54 receptions, 397 yards
Derek Loville: 218 att, 729 yds, 3.3 ypc, 87 rec, 662 yds
Terry Kirby: 134 att, 559 yds, 4.2 ypc, 52 rec, 439 yds
Adrian Murrell: 274 att, 1,042 yds, 3.8 ypc, 18 rec, 169 yds
Adrian Murrell: 193 att, 553 yds, 2.9 ypc, 49 rec, 335 yds
Michael Pittman: 184 att, 719 yds, 3.9 ypc, 73 rec, 579 yds
Charlie Garner: 182 att, 962 yds, 5.3 ypc, 91 rec, 941 yds
Tyrone Wheatley: 159 att, 678 yds, 4.3 ypc, 12 rec, 120 yds
Garner had 120 att, 553 yds, 4.6 ypc, 48 rec, 386 yds
That list isn't exactly a roster of past Pro-Bowlers, so it's safe to say that Trestman has not worked with someone of Forte's ability. Bears fans know Forte has the ability to be a 1,000/1,000 yard rusher/receiver. There is a great chance that with better OL play Trestman can get Forte to stay right around his career 4.4 YPC average and 1,530 career yards from scrimmage average. Forte could be in for a monster year.
So while much is made of offensive balance, it does not have to be 50/50. The Bears needed to run more in recent seasons because their OL was so inept at pass-blocking. However, hopefully Emery and Trestman will make over the line this offseason and the team will be able to sustain a more pass-heavy offensive balance and effectively (and efficiently, to use a Trestman word) run his offense.