What are these open positions? I'm going to make a wild guess that your looking to replace some talented and experienced Engineers who are reaching the end of their career. If so, the problem with filling those spots has less to do with the number of quality STEM graduates and more to do with changing demographics and some short sighted business practices which have become standard.
Engineering is a highly diverse field with innumerable different specializations and combinations of requisite experience. In the early days, the only way to get people with these skills was to train them alongside those at the forefront of their field, a.k.a. apprenticeship. Then came university engineering degree programs. At first they made a lot of sense, giving students with an interest in a field a basic understanding of the principles. That way they could be much more quickly and easily trained by a company. The problem was that this worked a little too well and ever more specialized programs proliferated and were filled as the trend toward an increasingly educated populace grew. Then during the post-WW2 population boom there were enough candidates in the workforce that companies found they could hire for almost any position directly, without having the overhead of the lower level apprentice engineers. This is when the idea that engineering was fungible began. Once that was taken for granted, companies began enacting policies based on short term profits instead of long term growth with the idea that they could just hire more or better engineers as they're needed. And this worked well until the entire industry instituted the same practices. By then population growth was slowing, so the pool of "qualified" (read: already trained) candidates shrank.
Now we are facing a problem of having an aging workforce with irreplaceable skill sets developed over decades and businesses are unwilling to train young Engineers for fear they will be poached by the competition. It's a typical game theory conundrum. The first company to start trying to grow their workforce internally will be out-competed by the rest, but if none do it we all lose.