It is a possibility. the OP should give it a try and put down a healthy
layer of manure this winter (that would adjust both the deficiency and
the pH). Is the soil clay? If so, the peat can provide early growing
room. But more important, I have had a number of situations with greens
(like tatsoi, chard, beet, cardoon, some cabbages and bok choi) where
they stalled and remained miserable. The causes I came up with (I have
sandy loam) were too little watering in the early going, too little
manure (humus and nitrogen) and too early/too late planting. These
little plants are fairly heavy feeders after all. Then there are bug
cycles. It looks like the miserable one ran into a generation or two of
caterpillars. If they get clipped when they are young, they will never
develop properly.

Right now I have two one foot sqaure patches of broccoli rabe. They are
separated by two feet, same bed, soil, and watering. One is three times
the size of the other, which is next to a stand of lemon balm. It could
be a bad companion, or it could be rodent tunnels underneath.

Single fixes do not often work in a garden. Systematic trials starting
from optimal conditions (late summer planting in Jiffy pots, high water
and manure) should allow the OP to find out how much he can get away
with. Hey, it takes five years to figure out how to manage a particular
garden.