James Bracey (FC avg 37) is now in the England squad. That surprises me, so I’m going to take a closer look.
37 is a very good average. But players with better averages are a long way from Test honours (his captain, Chris Dent, averages 38). Their stats are based on facing second division bowling. Thus I was expecting Bracey to average in the low 30s this year in the more challenging conference system.
Actually, Bracey has started 2021 brightly, with 478 runs in five games. That’s enough to boost his expected* Test average to 29 (+/-7)**. Here’s his record:

That +/-7 is important. England rate Bracey highly – with Lions tours already under his belt. Thus you might presume he’s doing better in the nets than in the middle – and put him at the upper end of the range, with an expected Test average of 33/34.
Context 1: batting in the top three. When cricket was a summer sport, it would be odd to pick a batsman averaging under 40. But top order batting in England in the spring and autumn is hard. Comparing Bracey to a selection of his peers (five number three batsmen in D2) from 2017-19, they averaged 30 and he outperformed them by 21%. Looking at this season, the top three clearly get the worst of the conditions. We should adjust expectations accordingly.

Context 2: Other bright young things. It looks like England are picking players on potential. If we look at the best batsmen born after 1997, most of them are in or around the squad.
Name | Age | Expected 2021 FC Avg | Tests |
OJ Pope | 23 | 50 | 17 |
JJ Bohannon | 24 | 40 | |
H Hameed | 24 | 39 | 3 |
DW Lawrence | 23 | 38 | 5 |
Z Crawley | 23 | 35 | 12 |
R Vasconcelos | 23 | 35 | |
SM Curran | 22 | 34 | 21 |
JR Bracey | 24 | 31 | Squad |
TC Lace | 22 | 30 | |
DM Bess | 23 | 30 | 14 |
GA Bartlett | 23 | 30 |
Context 3: First Class vs Test. I thought Zak Crawley (FC avg 32) made his Test debut far too soon. Yet he’s averaging more in Tests after 20 innings (34) than FC. It could be that performances against medium pace and junk spin should be excluded when working out who has international potential. I’ve started a ball by ball county database to get more detail – here’s the limited data so far, and yes – strip our the medium pacers and Bracey looks great. Watch out for his performances against off-spin though.

James Bracey is young, and bats in the top three – so his ability won’t be reflected in his average. He’s not (yet) a star, but it’s not inconceivable that in future he could average 35 in Tests and earn England’s troublesome number three spot.
*Expected Test average is calculated on the basis of runs scored, adjusted for difficulty, divided by number of times dismissed. Normally I’d use the last four years of data. It’s also adjusted for where they play: batting at Bristol is quite easy, I make it the fourth easiest ground for batting, inflating averages by 4%.
** Uncertainty: calculated with the formula Uncertainty = 2 * Average * (Times dismissed)^-0.5. This gives a 90% confidence estimate of someone’s ability, which gets more precise as the number of innings increases.