Depends on whose history you read. It is generally agreed on that because of the theological drift in the seminaries that the resurgence was given grounds for moving forward. The convention had not seen noticeable theological issues, though certainly political issues abounded. Lest we forget that one reality of the resurgence was that there were definite political scores to settle.
With several key missteps by the leftward faction that needed correction and the rightward faction used them in their quest for resurgence. Most of these were in the seminaries since they were, at the time, the most visible components of the convention at large.
Of course the key event occurred at NOBTS when a young PhD candidate was given a failing grade in a theological seminar and this became the proverbial straw that broke the camels back.
So I think you can say that the seminaries provided the kindling for the fire, but probably not the match.
From the perspective that the liberal drift of the seminaries sparked concern among the conservative SBC leadership -- notably those who elected Adrian Rogers to the Convention presidency -- I'd agree with that. But it was because the seminaries were drifting that action was taken, not that the seminaries prompted the conservative resurgency. Far from it, they were taking the SBC into a position of advocating a liberal theology that needed to be halted.
I do not know if this particular movement began in seminaries or not. However, we might assuredly say that Southern Baptist theological foundations arose from seminaries, by studied intent.
James P. Boyce (the first president of the Southern Baptist Theological Seminary, 1872-1879) wrote, for example, "The theological professor is to teach ministers, to place the truth, and all the errors connected with it in such a manner before his pupils, that they shall arrive at the truth without danger of any mixture of error therewith. He cannot do this if he has any erroneous tendencies, and hence his opinions must be expressly affirmed to be upon every point in accordance with the truth we believe to be taught in the Scriptures."
Generally, when people return to their roots, it is considered a conservative movement. A deviation from the roots is given rise by the abandonment of those fundamental principles. Certainly that was true of the general shift of the 1920's for the SBC. (As I somewhat vaguely recall.) The resurgence arose in the 60's-70's as a call for a return to the fundamentals.
On the other hand, I am not an SBC historian by any means. Just rendering a couple thoughts on the question.
The following is (I think) an excellent book related.
In the interest of full disclosure, I have not read this book, however, Dr. Richards, long ago was one of my professors, one which I had (and still have) the greatest of respect and admiration for.
As one who had some access to inside information from my father who worked at the BSSB and later at Southwestern Seminary and who planned and directed the music at the SBC meetings for 16 years, I will continue to maintain that the issue of rampant liberalism was a smokescreen for a power grab by the Pressler-Patterson-Rodgers faction.
They wanted control of the convention, and when they got it, they found out that they did not have near the support from the churches that they thought they had.
I refer you to the current state of decline of the SBC.
Actually, it's more like a ton.
I'm sure you have seen the statistics about declining membership and baptisms in SBC churches over the last decade at least.
I could also mention the numerous fights and lawsuits involving state conventions, colleges, churches, and seminaries.
However, as evidence of the detrimental effects of the takeover, I would refer you to the large number of churches that have removed "Baptist" from their names.
To a certain extent it was a power grab because the conservative element of the convention was being overlooked for appointments to governing boards.
We can argue all day long about whether the conservatives were acting out of principled concern for the direction of the convention or out of a hunger for power.
It depends on whose ox is being gored.
However, this much is true.
The convention was drifting to the left, primarily because of the left leaning faculty and staff in the seminaries.
There was much recrimination over the cleansing of the seminaries but the leftward trend was reversed, and in much less time than casual observers like me thought it would take.
Some good people were cast aside but I submit that the end resut has been positive.
The declines spoken of by Tim have been mainly within the last two or three years and they have been much less drastic than the declines being seen in the more liberal protestant denominations.
Were it not for the cleansing accomplished some 20 years ago, the SBC would be in a similar free fall.