McCormack should be back in the Villa squad for Saturday's clash with Wigan Athletic, but Baker and backup goalkeeper Mark Bunn are expected to miss out.
Aston Villa could only draw 2-2 with Nottingham Forest.
The 20-year-old midfielder's progress was hampered this past season by injuries and off-field issues.
The Irish defender has started Villa's past two games after making his Premier League debut in last month's 4-2 loss to Southampton.
Villa's recent 6-0 defeat to Liverpool has prompted suggestions that Brad Guzan could have the chance to reclaim the No. 1 spot from incumbent starter Mark Bunn.
Aston Villa suffered a heavy defeat to Liverpool in the Premier League on Sunday afternoon.
The veteran goalkeeper has kept three clean sheets in five Premier League starts since replacing Brad Guzan as Villa's No. 1 last month.
Former Aston Villa goalkeeper David James spoke to HITC Sport about the current goalkeeping situation at the club.
West Bromwich Albion played out a goalless draw with Aston Villa in the Premier League on Saturday afternoon.
Remi Garde's men left it late to see off the League Two side 2-0 in Tuesday night's FA Cup third round replay at Villa Park.