micdsguy-Good question "why coaches and scouts drool over LHPs".
Since there are many,many more righties than lefties, hitters naturally are going to get more experience and therefore become more proficient hitting against righthanded
pitchers. Lefthanders have the advantage or the element of "surprise"(for lack of a better term). Compare it to boxing, when a RH boxer faces a LH it's more difficult for
him to adjust as opposed to the LH adjusting to the rightie since he's probably faced
mostly righties in his career.
There is also the fact that you brought up about LH batters having a harder time against
lefties which gives a coach/manager more options when calling for relief pitchers.
Does seem kind of strange, doesn't it, that a lefty that throws 85 is as valuable as a righty that throws 90?