Well that went downhill quickly.
What leg was he for that 45.9r? Typically a running start is worth 0.5-1 second but even if we say he's good for a 47, that's very good speed for a high schooler running 4:07.
However, just looking at performances and not how much training they've had (remember GF has played soccer in the past in lieu of running, so it's not like he's an overtrained workhouse pumping out these times), GF still appears the more talented runner. His 3:42 is worth about a 1:47, and 4:07 1600m is great, but not really in the same league as a 3:42.
That said, I'm not seeing anything that would make me think Brazier can't break 1:47. Those splits are horrendous, especially for someone who is probably slightly better at the 400 than the mile (again, just based on his PRs). He needs to be going out harder and positive splitting. He's probably capable of going 52.0 then coming back in under 55.
All that said, as is always the big issue with having high schoolers break barriers, the competition is thin at the top, especially in the 800. At the dream mile you often have multiple kids running in the 4:02-4:04 range, which is enough to keep the pressure on someone to get under 4. If Brazier goes harder, how much of a lead would he have at 600 if he comes through in 1:19?
Anyone know when he plans to race again?