Yes is available nationally however you will only be able to get games if you are in the NY/North NJ market.
MASN and NESN are available depending where you live.
The best way to find out waht channels are available to would be here:
The Yes Network is available on FIOS Channel 595, part of the Extreme HD Package.
As ChanrlesH indicated it will NOT show the games unless you are in the Yankees Local Market due to league Blackout Rules.
The same blackout rules would apply to Dish and DirectTV.
I believe DirectTV carries YES, and NESN. At least that was the case when I lived In Baltimore. Thanks.
There are different rules for terrestrial vs. satellite which is why D-TV can offer out of market sports and Verizon (or any other cable system) can't.
When I had DirectTV I only had access to my local sports networks, unless I paid for a Sports Subscription or a package (NFL Sunday Ticket, MLB Package, etc).
Back in 2000 I had Direct-TV (in a distibuted apartment system) and I thought they had an option to pick up a bunch of the Fox Sports channels (out of market). Then again, it couild just be a "senior" moment .