Needless to say, on its face, the idea that an acting coach was brought in this late in production is slightly concerning. The issue isn't that the coach was needed, as mentioned, coaches are not unusual. The concerning bit is that nobody realized the coach was needed until filming had begun. Everything we've heard about Alden Ehrenreich up to this point was that he was the perfect person to play the role. We've been told he was the first to audition among literally thousands of people who submitted themselves. Something about his audition was so memorable that after Phil Lord and Chris Miller had auditioned every white male on the planet between the ages of 18 and 40, they still remembered Ehrenreich's performance. The perfect candidate can certainly still need a bit of help to get the job done, but how was this not noticed previously?