Well, keep in mind that the FASA game is from the mid-80's. Things in today's navy are a bit different than in the 80's, which were in turn different than the 60's.
In the late '60's, the US navy had a large number of WWII vintage gun cruisers and gun destroyers in the fleet. The new fangled missle ships being built were designed without significant guns and were classed as frigates. Keep in mind that the reliability of the missles in the 60s and 70s was a bit suspect.
In 1975, it was realized that all the old WWII ships were pretty much done and that the real power in the navy was in these new missle frigates. In 1975, all of the missle frigates were reclassified as either missle destroyers (DDG) or missle cruisers (CG). I guess the missles were getting "better". All of the old CA's and CL's were basically out of the fleet. The cruisers tended to be a bit more powerful or larger (in 1975 terms) than the destroyers.
In the 1980's, the US was building the Ticonderoga/Bunker Hill Cruisers, the Spurance Destroyers, and the Perry class frigates. The older cruisers and destroyers were smaller than these new ships, but had firepower "in between" the new cruisers and destroyers.
The Perry class frigates had a full suite of weapons, but are small ships with only a single shaft and and engine (vs two shafts on the larger ships). The Spurance Destroyers and Tico's shared the same hull and engines, but the Ticos had vastly superior sensors and missles. There were also four Kidd class destroyers which were basically Tico's without the fancy Aegis radars. The Kidd's could easily have been rated as cruisers.
***so bottom line: In the '80s, the frigates were small; the cruisers larger and the destroyers in between. Although there were exceptions, the cruisers tended to have better radars, missle control, and higher missle loadouts.
In the 1990's, the system became very muddled as all the cold war missle cruisers and missle destroyers were *all* retired and the US began builiding the Burke class destroyers. The Burkes are only slightly smaller than the new Tico's, carry basically the same Aegis radars and the same missles (only 75% load, however). The newest Burke destroyers even have helicopters like the cruisers. No kidding, the Burke class destroyers are better than almost anything in existance overseas. It is not clear that there are any tasks that a Tico cruiser can perform that a newer Burke can not also perform.
***So what does this mean for FASA? Don't know. This game was from the 80's, while the US navy was still undergoing the Reagan 600 ship buildup. From my perspective, the "Frigates" in this game are basically like "cruisers", except without the exploration and endurance capabilities. As a result, compared to a Connie, a Locknar does not need a secondary hull to carry stores and shuttles to still mount heavy firepower. The later Northampton and Chandley Frigates are large ships with heavy firepower, but I don't really see these ships on a "five year mission" like a contempory Enterprise class cruiser.