However, the lack of downward pressure on class B rates does not necessarily hold true for the submarkets. For example, in the 495 West submarket, there has been very little increase on the class B side. With class A properties holding relatively steady in price, "class B properties [are] getting increasingly aggressive for deals," he tells GlobeSt.com. The conundrum, for class B landlords, is to raise the incentive so class A tenants will look at the class B as a viable cost-saving option, while watching class A rents drop.

The most dramatic area to experience this pressure is in the 495 North submarket, according to Carroll. At the peak the difference between class A and class B space was 27% with class B asking lease rates only topping out at $17.22 per square foot. To maintain the price margin, class B landlords have been forced to lower rates to $16.37, "which is actually--if you adjust for the price of inflation--is the lowest class B asking lease rate in the submarket, so they're already at record low rent for class B properties," Carroll tells GlobeSt.com, but adds that this dynamic is not playing out in the more central markets of Boston.

Much of the buffer in price, generally across the Greater Boston market, is due to the limited construction pipeline. The CBD is looking at 1.4 million square feet on its way, while Cambridge is benefiting from an empty pipeline. Comparatively to the last downturn after the tech-bust, Boston is poised well for the future. "When things were getting bad at the end of [2008], there was 2.6 million square feet of construction in the pipeline," Carroll puts it into perspective. "When things were getting bad back in the Q4 of 2000--on the eve of the tech-bust--there was nine million square feet under construction." The new product, he explains, put a lot of downward pressure on lease rates of older product, but the pieces are not in place for serious deterioration this time around.

And despite rising available sublease space, it is still within the a 10% to 20% range which will not put significant pressure on direct availability asking rates, according to Carroll. Sublease space negatively affected rates after the tech-bust as it skyrocketed to 56% of the available space in East Cambridge, but sitting at roughly 16% now, it doesn't look to be as strong of a factor. RBJ notes that it is likely more sublease will come onto the market as companies downsize, but it will be from more established companies which are trimming their office needs, as opposed to younger companies failing and vacating space, as in 2001.