Alias. jbrack is likely what his primary SMTP address is (the actual email address connected to the account), and j.allen.brack is an alias that looks nicer for publishing.
Then it would fail DKIM. the whole point of DKIM and SPF is to verify that the email is in fact sent from the servers that the domain is connected to. The blizzard.com domain has both DKIM and SPF configured, and so if someone else tries to send an email that appears to be from that domain, the receiving email server will usually flag it as spam, and it will definitly flag that either SPF or DKIM has failed. This email shows that both has passed.