There's no way to arrive at a definitive answer to the question of whether or not straight ticket voting would have helped Republicans avoid the 2012 debacle, but just for the fun of it, I looked at all 400 State Reps elected last night, and when you establish criteria such as how well Obama and Romney and the gubernatorial candidates did (as a proxy for what might have been straight ticket voting in a given district), the data is not promising for Republicans.
To be sure, Democrats might well have failed to pick up single seats in places like Merrimack, Hudson, and Londonderry because Romney did significantly better than Obama in those places. However, it is very easy to find an equal number of places where Republicans would have possibly lost had straight ticket voting been in effect.
In fact--irony or ironies--one such place could have meant the defeat of one of the co-sponsors of the bill to bring back straight ticket voting--Ward 5 Nashua in which Don Lebrun was one of only three Republicans to win in the entire city. Look at the data, and one could easily conclude that straight ticket voting would have led to his defeat.
In Manchester, Republicans in Wards 11 and 12 and the float which included Wards 4, 5, 6, and 7 could well have lost had straight ticket voting been allowed.
Again, this is only a guessing game, and I won't go into all the numbers here because it would take too much time--you can either take my word for it or run an analysis yourself--but let's use just one example, one involving one of my favorite Republican Reps.
Republicans were virtually wiped out in Cheshire County. There are only three GOP Reps there now; John Hunt and Susan Emerson would have won in Rindge (in fact, they were unopposeed!), but Rep. Johnson would most likely not have survived in District 12 (Richmond-Swanzey). She won by only 29 votes (1915-1886); Barack Obama carried Swanzey 2133-1497; had straight ticket voting been in play, it is logical to assume that more than 29 of those who favored Obama would have marked a straight ticket and cost Rep. Johnson a well deserved win.
Just to run one result on the other side, let's look at Merrimack. Romney won the town 7750-6832, so it could well be argued that the eighth place Democratic winner (by 119 votes over the losing Republican; 5687-5568)) MIGHT not have won had staight ticket voting been in effect.
In Nashua Ward 5, bill sponsor Lebrun won by only 75 votes (2301-2226) in a ward Obama carried by 92 votes (2769-2678)--that wouldn't have sunk Lebrun, but Maggie Hassan, in the other race which would have come into play had straight ticket voting been allowed, won more than 700 votes (2945-2294); so the case could be made that Lebrun would have been sunk by the very thing he's now co-sponsoring.
It would be cruel to run numbers in too many other races, but Republicans who want to bring back straight ticket voting should heed the age-old admonition, "Be careful what you wish for." Straight ticket voting could be the death (politically speaking of course) of many of them.
My point in opposing straight ticket voting is to note again that it would prevent good people who work hard from getting elected and allow those who don't deserve to win (and probably are not willing to do the work) to slip in.
If some numbers guru genius with more time on his or her hands than I have wants to build a program to either verify or contradict what I've noted in passing, I'd love to see it.
Until then, I repeat--bringing back straight ticket voting will not hurt or harm either party overall; it will merely lead to the election of less qualified people!