Bortles was overdrafted in my opinion. Shouldn't have been a top 3 (or even top 20) pick. That said he actually wasn't bad at all in 2015 (under Greg Olsen). Regressed badly last year. He's working under his 3rd OC in 4 seasons. Consistency is so critical for QBs- the system they're in and the OC, etc.
Progress is almost never linear with a young QB. Like a stock chart you just need the line moving up and to the right overall....