Both the congressional and state legislature maps have been gerrymandered for incumbent protection. I believe in the last redistricting process, the proposed maps sent by both the GOP and Dems were similar. Also worth pointing out that the Democrats won the popular vote in 2015.
For Dem incumbents yes. For Republican incumbents no. The Democratic party went out of their way to gerrymander a potential Democratic district in Monmouth County in the 11th district and also a 4 county snake in the 16th district, both of which were safe under the 2001 map.
Bipartisan 10-member New Jersey Redistricting Commission
5 Democrats
5 Republicans
Trivia: What happens when those 10 do not agree on a legislative map?
An 11th member is appointed by a supreme court justice to break the tie.
Edit: If I may add, Alan Rosenthal was a great choice. Literally, you could have not have asked for a better person to split the tie.