a foolish consistency is the hobgoblin of little minds
go nowhere
if it ain't broke, don't fix it
mobility
nonadaptation
counterproductive
let the grass grow under one's feet
nonimprovement
flat out
qualitative leap
rigid
inflexible
imperfectibility
unbending
little strokes fell great oaks
inconsistent
misfire
law of diminishing returns
nonadjustment
sophomore slump
inadaptation
high-hanging fruit
incompatibility
rough edges
creeping normality
failure
checkered
leave a lot to be desired
flow-on effect
apologize
unlikely
die on the vine
apologise
clash
go over like a lead balloon
catch
uptick
be careful what you wish for
insecure
gimmick
nonadvancement
zoom
nonconform
miss the mark
unprogress
irreversibility
lability
misoptimize
unimprovement
strike out looking
nonfailure
self-defeating
adaptate
flaw
downtick
velleitary
unadjustment
inexact
push one's luck
fossilization
progresslessness
nonprogress
chaotic
unsettled
mismeet
uncontriving
disadaptation
unready
fluctuance
unadaptability
overchange
unsuccess
underachieve
uncommercial
underperform
static
tough tuchus
tough toodles
unresolve
nonfixation
tough titty
conflict
tough cookies
plateau effect
scrape the bottom of the barrel
erratic
more is more
failing
spotty
uneven
lameness
dripping water hollows a stone
imperfection
noncontinuity
weakness
pseudoimprovement
scratchy