Unless they're working on new features which are needed tomorrow, one dev seems fine in the interim. The number of sysadmins is more important to keeping a site running, but of course that's not what's in TC's headline.
Now if we are talking devops, I can agree. Engineering teams this small need to wear many hats; I think jedberg has been said to have helped in development efforts, if my memory of past blogs serves right.
A lot of our sysadmin time is spent tracking down bugs in the stuff we use (like Cassandra) and doing tuning and automation.
Also, I do a lot of the other business stuff, so at best I'm a part time sysadmin right now.
We do pretty much do "devops" though. A lot of the work of Neil, our programmer, is tracking down bugs due to data inconsistencies due to hardware problems.