Increase in the Democratic Percentage of the Vote by County, 2010-14The number on each county is the number of percentage points the Democratic vote increased by from 2010 from 2014. For example, Dan Onorato got 28.9% of the vote in Lancaster County and Tom Wolf got 40.9%, so a 12.0 is displayed. Red counties had a smaller-than-average swing toward Wolf; blue counties had a larger-than-average one. All election data in this post comes from www.uselectionatlas.org. Since I didn't have enough space to label the counties with their names, you can find that here.
Where Wolf increased less than average: The rural northeastern corner of the state (with the odd exception of Wayne County) and the outlying population centers of Philadelphia, Pittsburgh, and Erie stand out as areas where Gov. Wolf didn't improve as much as he did statewide. The far northeast is the epicenter of fracking in Pennsylvania, so it might be the one area where former Gov. Tom Corbett's association with the gas industry helped him. Say what you want about fracking, but it doesn't seem to be terribly unpopular in the areas where it's actually taking place.
(Fun fact: Blogger still autocorrects "fracking" to "tracking".)
As for Philly and Pittsburgh, it's possible that Philadelphia (the second-lowest increase in the state for Wolf) was a "dead cat bounce" for Corbett, who didn't have that many voters in Philly to lose in the first place. (He went from 17.1% there in 2010 to 12% in 2014.) The fact that Wolf defeated three Philly-based candidates in the primary may have hurt him in the Southeast, and the fact that 2010 was between two Allegheny County candidates, while Tom Corbett was the only candidate from the area in 2014, may have stemmed Corbett's losses in Pittsburgh.
Where Wolf increased more than average: The central part of the state, ranging from Fayette and Venango counties in the west to Lackawanna County (i.e., Scranton and its immediate neighbors) in the northeast. The biggest swings toward Wolf were in Forest County in the northwest (which has the state's second-smallest population and a large state prison, so it might be an outlier), Huntingdon County (immediately south of State College), and a belt stretching from Union and Snyder counties to Schuylkill County. The anthracite coal region, with the notable exception of Luzerne County, swung hard to Wolf.
The 409*-pound elephant in the room is Gov. Corbett's role in the firing of Joe Paterno. To make a long story short, there is a perception among some Penn State fans, fairly or otherwise, that Corbett (the attorney general from 2005 to 2011) dragged his feet on the Jerry Sandusky investigation until after he was elected governor, then made Paterno a scapegoat. That would certainly explain Corbett's unpopularity in Centre and surrounding counties, but that wasn't the only, or even the worst, area of decline for Corbett.
Another explanation might be the different dynamics of 2014 from 2010. The 2010 gubernatorial election was between two non-incumbents for an open seat at the high tide of anti-Obamacare sentiment, so the conservative voters of central Pennsylvania were motivated to vote against Democrats. In 2014, anti-Obamacare sentiment had faded (as did memories of former Gov. Ed Rendell, never too popular in rural areas), and Gov. Corbett had his own record and controversies to defend. The GOP did its best to portray Wolf, state Secretary of Revenue in 2007 and 2008, as Ed Rendell's tax collector, but it's difficult to portray a Jeep-driving businessman from York County (note Wolf's improvements in York and surrounding counties) as an extreme liberal.
*See what I did there?