You might be right. According to openhub Firefox had 1121 contributors last year. Compared to that Chromium had 1919 contributors. Not all of them work for Mozilla and Google respectively and not all employees commit to the code base...
They just seem to be not very good at it, because from 40 -> 50 - memory usage is much worse than previous versions (Yes, I know switching to the MP model has to do with it, but if your architectural changes hurt usability for security I consider that quite poor), the developer tools are still trash, and performance is still worse than chrome.