As you pointed out, Alonso was also a disaster last season. So, you can't exactly only look at his OK games.
Moreover if the bench selection over the last month is anything to go by, it seems like Emerson is ahead of Alonso in the pecking order. Okay, Alonso was suspended for the first 2 Champions League games but he hasn't been in the Premier League matchday squad since that disaster at West Brom. Only time he's made the matchday squad was the match against Rennes and even then, it was because clubs were allowed 12 subs on the bench in the Champions League.